UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549


FORM N-CSRS


CERTIFIED SHAREHOLDER REPORT OF REGISTERED MANAGEMENT INVESTMENT
COMPANIES


Investment Company Act file number 811-5850
                                   811-10171

Name of Fund:  Merrill Lynch Senior Floating Rate Fund, Inc.
               Master Senior Floating Rate Trust

Fund Address:  P.O. Box 9011
               Princeton, NJ  08543-9011

Name and address of agent for service:  Terry K. Glenn, President,
Merrill Lynch Senior Floating Rate Fund, Inc., 800 Scudders Mill
Road, Plainsboro, NJ,  08536.  Mailing address:  P.O. Box 9011,
Princeton, NJ, 08543-9011

Registrant's telephone number, including area code:  (609) 282-2800

Date of fiscal year end: 08/31/04

Date of reporting period: 09/01/03 - 02/29/04

Item 1 - Report to Stockholders



(BULL LOGO)
Merrill Lynch Investment Managers


www.mlim.ml.com


Merrill Lynch
Senior Floating Rate
Fund, Inc.


Semi-Annual Report
February 29, 2004



Merrill Lynch Senior Floating Rate Fund, Inc. seeks as high a level
of current income and such preservation of capital as is consistent
with investment in senior collateralized corporate loans made by
banks and other financial institutions.

This report, including the financial information herein, is
transmitted for use only to the shareholders of Merrill Lynch Senior
Floating Rate Fund, Inc. for their information. It is not a
prospectus, circular or representation intended for use in the
purchase of shares of the Fund or any securities mentioned in this
report. Past performance results shown in this report should not be
considered a representation of future performance.

A description of the policies and procedures that the Fund uses to
determine how to vote proxies relating to portfolio securities is
available (1) without charge, upon request, by calling toll-free
1-800-MER-FUND (1-800-637-3863); (2) on www.mutualfunds.ml.com;
and (3) on the Securities and Exchange Commission's website at
http://www.sec.gov.



Merrill Lynch Senior Floating Rate Fund, Inc.
Box 9011
Princeton, NJ
08543-9011



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Merrill Lynch Senior Floating Rate Fund, Inc.


Officers and Directors/Trustees


Terry K. Glenn, President and Director/Trustee
Ronald W. Forbes, Director/Trustee
Cynthia A. Montgomery, Director/Trustee
Kevin A. Ryan, Director/Trustee
Roscoe S. Suddarth, Director/Trustee
Richard R. West, Director/Trustee
Edward D. Zinbarg, Director/Trustee
Kevin J. Booth, Vice President
Joseph P. Matteo, Vice President
Donald C. Burke, Vice President and Treasurer
Phillip S. Gillespie, Secretary


Charles R. Reilly, Director/Trustee of Merrill Lynch Senior Floating
Rate Fund, Inc., has recently retired. The Fund's Board of
Directors/Trustees wishes Mr. Reilly well in his retirement.



Custodian
The Bank of New York
100 Church Street
New York, NY 10286


Transfer Agent
Financial Data Services, Inc.
4800 Deer Lake Drive East
Jacksonville, FL 32246-6484
800-637-3863



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



A Letter From the President


Dear Shareholder

As I write to you at February month-end, fixed income markets in the
United States continued to reward those investors willing to accept
greater risk. The high yield market, as measured by the Credit
Suisse First Boston High Yield Index, provided a return of +10.88%
over the past six months and +25.17% for the 12-month period ended
February 29, 2004. In other areas of fixed income, investment grade
corporate bonds, as measured by the Merrill Lynch Corporate Master
Index, returned +6.59% and +8.11% for the six-month and 12-month
periods ended February 29, 2004, respectively. Treasury issues, as
measured by the Merrill Lynch U.S. Treasuries 1-10 Years Index,
returned +3.16% and +2.73% for the six-month and 12-month periods
ended February 29, 2004, respectively.

At the same time, equity markets maintained their positive momentum
from year-end 2003. For the six-month and 12-month periods ended
February 29, 2004, Standard & Poor's (S&P) 500 Index returned
+14.59% and +38.52%, respectively. Much of the boost came from
improving economic conditions in the United States.

The major signposts as we enter 2004 indicate that we are seeing a
shift from economic growth fueled primarily by fiscal and monetary
stimulus to a broader-based, self-sustaining economic expansion.
Gross domestic product growth, which peaked at an annualized rate of
8.2% in the third quarter of 2003, was 4.1% in the fourth quarter. A
similar level of growth is expected in the first quarter of 2004.
For its part, the Federal Reserve Board has reiterated its
willingness to keep short-term interest rates at current low levels
to ensure the economy's strength.

Accompanying the increase in economic activity was an improvement
in corporate earnings. By February 10, 2004, 392 of the S&P 500
companies had reported their fourth-quarter 2003 results, and 67.6%
of those exceeded expectations. In the meantime, the American
consumer, who continued to spend despite the faltering economy, may
get further incentive from another round of Federal tax refunds this
year.

At Merrill Lynch Investment Managers, we believe the events and
efforts of 2003 left us with a much stronger economy and that recent
optimism suggests it is time for investors to consider what can go
right in 2004. We encourage you to revisit your portfolio and your
asset allocation startegy to ensure you are well positioned to take
advantage of the opportunities that lie ahead.

We thank you for trusting Merrill Lynch Investment Managers with
your investment assets, and we look forward to serving you in the
months and years ahead.


Sincerely,



(Terry K. Glenn)
Terry K. Glenn
President and Director/Trustee



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



A Discussion With Your Fund's Portfolio Managers


The Fund participated in an aggressive rally in the leveraged loan
market, and ended the period with a total return exceeding that of
the benchmark CSFB Leveraged Loan Index


How did the Fund perform during the six-month period?

For the six-month period ended February 29, 2004, the Common
Stock of Merrill Lynch Senior Floating Rate Fund, Inc. had a net
annualized yield of 3.74%, based on a period-end per share net asset
value of $8.84 and $.165 per share income dividends. Over the same
period, the total investment return on the Fund's Common Stock was
+7.23%, based on a change in per share net asset value from $8.40 to
$8.84, and assuming reinvestment of $.165 per share ordinary income
dividends. These results compare to the +4.68% total return of the
Credit Suisse First Boston (CSFB) Leveraged Loan Index for the same
period. The increase in the mark-to-market valuation of the
portfolio, combined with the current income being distributed, led
to a total return that significantly outpaced that of the benchmark
CSFB Leveraged Loan Index.


What were the primary market and economic developments that affected
the Fund?

In our last report to shareholders, we noted that the leveraged loan
market's positive momentum had declined following a monthly return
peak of +1.41% in April 2003. That period ended on August 31, 2003
with an August monthly return of +.21%. In this six-month period
ended February 29, 2004, market returns rebounded from August's
relative low point, although the high April 2003 monthly return was
not surpassed.

In the past six months, inflows into the loan market via new
collateralized debt obligations, prime funds and hedge funds
exceeded the amount of new issues coming to market. This helped to
maintain a strong bid on loans in the secondary market as loan
managers competed to put their cash to work. In the primary market,
pricing was equally competitive with market participants routinely
receiving new-issue allocation amounts well below their commitment
levels.

Adding to the levels of cash held by loan managers was a steady
stream of refinancings. The refinancing activity was initiated by
issuers seeking to take advantage of the new lower market spreads,
which had steadily dropped throughout the period. According to
Standard & Poor's (S&P) Leveraged Commentary and Data, the new-issue
spread for BB/BB- institutional loans was 235 basis points (2.35%)
in February 2004, compared to 295 basis points in September 2003.
For B/B+ loans, the spread was 294 basis points in February 2004
versus 350 basis points in September 2003.

A steady decline in the default rate over the past year also
contributed to investor demand for the leveraged loan asset class.
For example, the lagging 12-month default rate for the S&P/LSTA
Leveraged Loan Index was 1.61% on February 29, 2004 versus 2.91% on
September 30, 2003 and 5.01% on February 28, 2003. The floating rate
nature of leveraged loans also has been a desired feature among
those investors seeking to add an interest-rate-defensive position
to their portfolio in anticipation of a Federal Reserve Board move
to increase interest rates.


What changes were made to the portfolio during the period?

From a sector perspective, we continued to emphasize those
industries with strong asset values and stable cash flow
characteristics. Our highest concentration remained in cable--U.S.,
followed by wireless communications, utilities, chemicals and
service. The continued rally in cable television, which bottomed out
in 2002, provided a significant amount of the price appreciation
performance in this period. In fact, much of the positive impact
during the period was still attributable to the sectors that hurt
performance in 2002. These included those sectors in which we
traditionally have favored and benefited from an overweighting, such
as cable television, utilities and wireless communications. Our
investment hypothesis has been that these are strong cash-flowing
industries with significant underlying asset values. We believe
their market prices suffered in 2002 either for technical reasons,
such as fallout from corporate scandals from isolated pockets of the
sector, or from too much total leverage (rather than senior
leverage), or from a combination. Our investment thesis followed
that as the tide of technical price pressures ebbed, our senior,
secured positions in these companies would regain their price
footing. The performance of these sectors, in particular, has
validated our strategy of weathering the storm and holding our
positions.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



How would you characterize the portfolio's position at the close of
the period?

At period end, Master Senior Floating Rate Trust, of which the Fund
invests all of its assets, was comprised of 147 issuers spread among
32 industries. Compared to the CSFB Leveraged Loan Index as of the
same date, the Trust was underweight Ba and above issues (40.3%
versus 48.9% for the Index), overweight B (38.5% versus 30.23%),
overweight Caa or below (8.4% versus 6.3%) and underweight not rated
issues (13% versus 14.6%). It should be noted that approximately
half of our overweight in Caa or below issues is attributable to
positions in the Adelphia Communications family of names. Despite
the fact that Adelphia has been in bankruptcy for more than a year,
its strong assets and associated cash flow has allowed the company
to continue to fully service its bank loan interest obligations and
has kept the loans trading like paper of a much higher rating
quality. In addition, if we include the Trust's positions in high-
quality cash equivalents, the distribution is as follows: Ba and
above, 41.9%; B, 38.5%; Caa or below, 13.5%; and Not Rated, 6.1%.

Overall, the Fund took part in an aggressive rally in the leveraged
loan market during the six-month period. The rally, however, has led
to a refinancing boom that has resulted in lower spreads and more
cash being put into the hands of loan managers. Given the prepayable
nature of loans, it is unlikely that there will be a significant
amount of additional price appreciation based on their current
trading levels. This, combined with lower spreads on new-issue
loans, will likely lead to a moderation in the monthly total return
percentages over the next period. Given this challenging secondary
and new-issue market, we remain vigilant in our analysis of the
structure and terms of potential leveraged loan investments.


Kevin J. Booth
Vice President and Portfolio Manager


Joseph P. Matteo
Vice President and Portfolio Manager


March 26, 2004



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Statements of Assets and Liabilities                                          Merrill Lynch Senior Floating Rate Fund, Inc.


As of February 29, 2004
                                                                                                   
Assets

               Investment in Master Senior Floating Rate Trust, at value
               (identified cost--$862,694,054)                                                               $  781,125,058
               Prepaid registration fees                                                                            385,602
                                                                                                            ---------------
               Total assets                                                                                     781,510,660
                                                                                                            ---------------

Liabilities

               Payables:
                  Dividends to shareholders                                               $       864,136
                  Other affiliates                                                                169,500
                  Administrator                                                                   149,565         1,183,201
                                                                                          ---------------
               Accrued expenses                                                                                     152,203
                                                                                                            ---------------
               Total liabilities                                                                                  1,335,404
                                                                                                            ---------------

Net Assets

               Net assets                                                                                   $   780,175,256
                                                                                                            ===============

Net Assets Consist of

               Common Stock, par value $.10 per share; 1,000,000,000 shares authorized                      $     8,824,433
               Paid-in capital in excess of par                                                               1,153,868,979
               Accumulated distributions in excess of investment income--net              $     (103,485)
               Accumulated realized capital losses on investments allocated from the
               Trust--net                                                                   (300,845,675)
               Unrealized depreciation on investments allocated from the Trust--net          (81,568,996)
                                                                                          ---------------
               Total accumulated losses--net                                                                  (382,518,156)
                                                                                                            ---------------
               Net Assets--Equivalent to $8.84 per share based on 88,244,334 shares of
               capital stock outstanding                                                                    $   780,175,256
                                                                                                            ===============

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Statement of Operations                                                       Merrill Lynch Senior Floating Rate Fund, Inc.


For the Six Months Ended February 29, 2004
                                                                                                   
Investment Income Allocated from the Trust--Net

               Net investment income allocated from the Trust:
                  Interest (including $551,776 from affiliates)                                             $    20,080,726
                  Facility and other fees                                                                           362,180
                  Expenses                                                                                      (3,912,155)
                                                                                                            ---------------
               Net investment income allocated from the Trust                                                    16,530,751
                                                                                                            ---------------

Expenses

               Administration fees                                                        $       967,831
               Transfer agent fees                                                                363,888
               Tender offer fees                                                                  250,191
               Printing and shareholder reports                                                    45,211
               Registration fees                                                                   19,562
               Professional fees                                                                    9,216
               Other                                                                                5,789
                                                                                          ---------------
               Total expenses                                                                                     1,661,688
                                                                                                            ---------------
               Investment income--net                                                                            14,869,063
                                                                                                            ---------------

Realized & Unrealized Gain (Loss) on Investments Allocated from the Trust--Net

               Realized loss on investments allocated from the Trust--net                    (28,078,553)
               Change in unrealized depreciation on investments allocated from the
               Trust--net                                                                      67,485,526
                                                                                          ---------------
               Total realized and unrealized gain on investments allocated from the
               Trust--net                                                                                        39,406,973
                                                                                                            ---------------
               Net Increase in Net Assets Resulting from Operations                                         $    54,276,036
                                                                                                            ===============

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Statements of Changes in Net Assets                                           Merrill Lynch Senior Floating Rate Fund, Inc.

                                                                                            For the Six          For the
                                                                                            Months Ended        Year Ended
                                                                                            February 29,        August 31,
Increase (Decrease) in Net Assets:                                                              2004              2003++
                                                                                                   
Operations

               Investment income--net                                                     $    14,869,063   $    41,897,085
               Realized loss on investments and allocated from the Trust--net                (28,078,553)      (36,800,954)
               Change in unrealized depreciation on investments allocated from the
               Trust--net                                                                      67,485,526        70,358,217
                                                                                          ---------------   ---------------
               Net increase in net assets resulting from operations                            54,276,036        75,454,348
                                                                                          ---------------   ---------------

Dividends to Shareholders

               Investment income--net                                                        (14,758,132)      (43,357,390)
                                                                                          ---------------   ---------------
               Net decrease in net assets resulting from dividends to shareholders           (14,758,132)      (43,357,390)
                                                                                          ---------------   ---------------

Capital Share Transactions

               Net decrease in net assets derived from capital share transactions            (57,662,329)     (297,760,644)
                                                                                          ---------------   ---------------

Net Assets

               Total decrease in net assets                                                  (18,144,425)     (265,663,686)
               Beginning of period                                                            798,319,681     1,063,983,367
                                                                                          ---------------   ---------------
               End of period*                                                             $   780,175,256   $   798,319,681
                                                                                          ===============   ===============
                  *Accumulated distributions in excess of investment income--net          $     (103,485)   $     (214,416)
                                                                                          ===============   ===============

++On February 10, 2003, the Fund converted from a stand-alone
investment company to a "feeder" fund that seeks to achieve its
investment objective by investing all of its assets in the Trust,
which has the same investment objective as the Fund. All investments
are made at the Trust level. This structure is sometimes called a
"master/feeder" structure.

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Financial Highlights                                                          Merrill Lynch Senior Floating Rate Fund, Inc.

                                                             For the Six
The following per share data and ratios have been derived    Months Ended
from information provided in the financial statements.       February 29,         For the Year Ended August 31,
Increase (Decrease) in Net Asset Value:                          2004      2003+++++      2002         2001          2000
                                                                                               
Per Share Operating Performance

               Net asset value, beginning of period          $     8.40   $     8.05   $     8.82   $     9.45   $     9.73
                                                             ----------   ----------   ----------   ----------   ----------
               Investment income--net                            .16***          .38         .43           .79          .77
               Realized and unrealized gain (loss) on
               investments and allocated from the Trust--net        .44          .36        (.77)        (.62)        (.28)
                                                             ----------   ----------   ----------   ----------   ----------
               Total from investment operations                     .60          .74        (.34)          .17          .49
                                                             ----------   ----------   ----------   ----------   ----------
               Less dividends from investment income--net         (.16)        (.39)        (.43)        (.80)        (.77)
                                                             ----------   ----------   ----------   ----------   ----------
               Net asset value, end of period                $     8.84   $     8.40   $     8.05   $     8.82   $     9.45
                                                             ==========   ==========   ==========   ==========   ==========

Total Investment Return**

               Based on net asset value per share              7.23%+++        9.61%      (4.09%)        1.52%        5.44%
                                                             ==========   ==========   ==========   ==========   ==========

Ratios to Average Net Assets

               Expenses, excluding interest expense++            1.44%*        1.45%        1.41%        1.36%        1.31%
                                                             ==========   ==========   ==========   ==========   ==========
               Expenses++                                        1.44%*        1.46%        1.41%        1.36%        1.31%
                                                             ==========   ==========   ==========   ==========   ==========
               Investment income--net                            3.84%*        4.81%        5.07%        8.39%        8.17%
                                                             ==========   ==========   ==========   ==========   ==========

Leverage

               Average amount of borrowings during the
               period (in thousands)                                 --   $8,138++++   $    3,374           --           --
                                                             ==========   ==========   ==========   ==========   ==========
               Average amount of borrowings per share
               during the period                                     --   $  .07++++   $      .02           --           --
                                                             ==========   ==========   ==========   ==========   ==========

Supplemental Data

               Net assets, end of period (in thousands)      $  780,175   $  798,320   $1,063,983   $1,778,295   $2,492,591
                                                             ==========   ==========   ==========   ==========   ==========
               Portfolio turnover from the Trust                 31.37%       56.56%       89.46%       50.82%       59.59%
                                                             ==========   ==========   ==========   ==========   ==========

*Annualized.

**Total investment returns exclude the early withdrawal charge, if
any. The Fund is a continuously offered closed-end fund, the shares
of which are offered at net asset value. No secondary market for the
Fund's shares exists. If applicable, the Fund's investment adviser
waived a portion of its management fee. Without such waiver, the
Fund's returns would have been lower.

***Based on average shares outstanding.

++Includes the Fund's share of the Trust's allocated expenses.

++++Reflects the average amount of borrowings of the Fund prior to
the Fund's conversion from a stand-alone investment company to a
"feeder" fund on February 10, 2003.

+++Aggregate total investment return.

+++++On February 10, 2003, the Fund converted from a stand-alone
investment company to a "feeder" fund that seeks to achieve its
investment objective by investing all of its assets in the Trust,
which has the same investment objective as the Fund. All investments
are made at the Trust level. This structure is sometimes called a
"master/feeder" structure.

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Notes to Financial Statements
Merrill Lynch Senior Floating Rate Fund, Inc.


1. Significant Accounting Policies:
Merrill Lynch Senior Floating Rate Fund, Inc. (the "Fund") is
registered under the Investment Company Act of 1940, as amended, as
a continuously offered, non-diversified, closed-end management
investment company. The Fund seeks to achieve its investment
objective by investing all of its assets in the Master Senior
Floating Rate Trust (the "Trust"), which has the same investment
objective as the Fund. The value of the Fund's investment in the
Trust reflects the Fund's proportionate interest in the net assets
of the Trust. The performance of the Fund is directly affected by
the performance of the Trust. The financial statements of the Trust,
including the Schedule of Investments, are included elsewhere in
this report and should be read in conjunction with the Fund's
financial statements. The Fund's financial statements are prepared
in conformity with accounting principles generally accepted in the
United States of America, which may require the use of management
accruals and estimates. These unaudited financial statements reflect
all adjustments, which are, in the opinion of management, necessary
to a fair statement of the results for the interim period presented.
All such adjustments are of a normal, recurring nature.

The percentage of the Trust owned by the Fund at February 29, 2004
was 80.8%. The following is a summary of significant accounting
policies followed by the Fund.

(a) Valuation of investments--The Fund records its investment in the
Trust at fair value. Valuation of securities held by the Trust is
discussed in Note 1a of the Trust's Notes to Financial Statements,
which are included elsewhere in this report.

(b) Investment income and expenses--The Fund records daily its
proportionate share of the Trust's income, expenses and realized and
unrealized gains and losses. In addition, the Fund accrues its own
expenses.

(c) Income taxes--It is the Fund's policy to comply with the
requirements of the Internal Revenue Code applicable to regulated
investment companies and to distribute substantially all of its
taxable income to shareholders. Therefore, no Federal income tax
provision is required.

(d) Prepaid registration fees--Prepaid registration fees are charged
to expense as the related shares are issued.

(e) Dividends and distributions--Dividends from net investment
income are declared daily and paid monthly. Distributions of capital
gains are recorded on the ex-dividend dates.

(f) Investment transactions--Investment transactions in the Trust
are accounted for on a trade date basis.


2. Transactions with Affiliates:
The Fund has entered into an Administration Agreement with Fund
Asset Management, L.P. ("FAM"). The general partner of FAM is
Princeton Services, Inc. ("PSI"), an indirect, wholly-owned
subsidiary of Merrill Lynch & Co., Inc. ("ML & Co."), which is the
limited partner. The Fund pays a monthly fee at an annual rate of
..25% of the Fund's average daily net assets for the performance of
administrative services (other than investment advice and related
portfolio activities) necessary for the operation of the Fund.

Financial Data Services, Inc. ("FDS"), a wholly-owned subsidiary of
ML & Co., is the Fund's transfer agent.

For the six months ended February 29, 2004, FAM Distributors, Inc.
("FAMD"), a wholly-owned subsidiary of Merrill Lynch Group, Inc.,
earned early withdrawal charges of $78,585 relating to the tender of
the Fund's shares.

Certain officers and/or directors of the Fund are officers and/or
directors of FAM, PSI, FAMD, FDS, and/or ML & Co.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Notes to Financial Statements (concluded)
Merrill Lynch Senior Floating Rate Fund, Inc.


3. Capital Share Transactions:
Transactions in capital shares were as follows:


For the Six Months                                           Dollar
Ended February 29, 2004                   Shares             Amount

Shares sold                            2,989,424    $    25,890,123
Shares issued to shareholders
   in reinvestment of dividends          806,389          7,003,135
                                 ---------------    ---------------
Total issued                           3,795,813         32,893,258
Shares tendered                     (10,549,037)       (90,555,587)
                                 ---------------    ---------------
Net decrease                         (6,753,224)    $  (57,662,329)
                                 ===============    ===============



For the Year Ended                                           Dollar
August 31, 2003                           Shares             Amount

Shares sold                            1,561,464    $    12,799,507
Shares issued to shareholders
   in reinvestment of dividends        2,395,510         19,319,880
                                 ---------------    ---------------
Total issued                           3,956,974         32,119,387
Shares tendered                     (41,139,108)      (329,880,031)
                                 ---------------    ---------------
Net decrease                        (37,182,134)    $ (297,760,644)
                                 ===============    ===============


4. Capital Loss Carryforward:
On August 31, 2003, the Fund had a net capital loss carryforward of
$246,934,067, of which $1,471,065 expires in 2004, $3,278,446
expires in 2005, $4,468,275 expires in 2006, $3,365,959 expires in
2007, $28,290,011 expires in 2008, $64,746,799 expires in 2009,
$87,904,309 expires in 2010 and $53,409,203 expires in 2011. This
amount will be available to offset like amounts of any future
taxable gains.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Schedule of Investments                                                                   Master Senior Floating Rate Trust


                     S&P      Moody's  Face
Industry++           Rating   Rating   Amount     Senior Secured Floating Rate Loan Interests**                     Value
                                                                                              
Automotive           BB       Ba2    $ 1,756,522  TRW Automotive Inc., Term B, due 2/28/2011                 $    1,789,300
Equipment--0.6%                                   Tenneco Automotive Inc.:
                     B        B1       2,482,759      Term B, due 12/12/2010                                      2,528,275
                     B        B1       1,117,241      Term B-1, due 12/12/2010                                    1,137,724
                                                                                                             --------------
                                                                                                                  5,455,299

Broadcasting--0.6%   B+       Ba3      3,970,000  Cumulus Media Inc., Term D, due 3/28/2010                       4,029,550
                     BB       Ba2      1,843,600  Sinclair Broadcasting Group Inc., Term B, due 12/31/2009        1,865,329
                                                                                                             --------------
                                                                                                                  5,894,879

Cable--U.S.--22.7%   BB       Ba3      4,645,865  CC VI Operating Company LLC, Term B, due 11/12/2008             4,512,877
                     B        B2      14,602,000  CC VIII Operating Company LLC, Term B, due 2/02/2008           14,401,223
                     NR*      NR*     50,000,000  Century Cable Holdings LLC, Term, due 6/30/2009                47,947,900
                                                  Charter Communications Holdings:
                     NR*      NR*     57,723,030      Term B, due 3/18/2008                                      56,287,977
                     NR*      NR*      5,000,000      Term B, due 9/18/2008                                       4,875,695
                     B-       B2       7,371,212  Charter Communications Operating LLC, Incremental Term,
                                                  due 9/18/2008                                                   7,179,767
                     B        Ba3      9,500,000  Falcon Holdings Group, Term C, due 12/31/2007                   9,254,587
                                                  Frontiervision Operating Partners LP:
                     D        B2       3,582,057      Term A, due 9/30/2005                                       3,562,653
                     D        B2      15,668,000      Term B, due 3/31/2006                                      15,583,126
                     NR*      Caa1     9,975,000  Hilton Head/UCA Inc., Term B, due 3/31/2008                     9,625,875
                                                  Inmarsat Investments Limited:
                     BB-      Ba3      4,625,000      Term B, due 1/23/2017                                       4,646,196
                     BB-      Ba3      4,625,000      Term C, due 1/23/2017                                       4,646,196
                                                  Insight Midwest Holdings, LLC:
                     BB+      Ba3      4,000,000      Incremental Term, due 12/31/2009                            4,032,500
                     BB+      Ba3      5,500,000      Term B, due 12/31/2009                                      5,537,433
                     D        B2      23,500,000  Olympus Cable Holdings LLC, Term B, due 9/30/2010              22,391,105
                     BB       Ba2        700,000  Panamsat Corp., Term, due 12/31/2008                              711,375
                     B-       B3       4,537,831  Pegasus Communications, Term, due 4/30/2005                     4,462,199
                                                                                                             --------------
                                                                                                                219,658,684

Chemicals--6.0%      NR*      NR*      3,654,871  CII Carbon LLC, Term, due 6/25/2008                             3,508,677
                     NR*      NR*      7,182,700  Cedar Chemical Corp., Term B, due 10/31/2003 (d)                  395,049
                     B+       Ba3        695,652  Ethyl Corporation, Term, due 4/30/2009                            701,449
                                                  Huntsman International LLC:
                     B        B1      19,634,958      Term B, due 6/30/2007                                      19,827,224
                     B        B1      19,634,958      Term C, due 6/30/2008                                      19,843,580
                     BB-      B1       1,000,000  KRATON Polymers LLC, Revolving Term, due 12/24/2010             1,017,917
                     BB-      B1       6,200,000  Nalco Company, Term, due 11/04/2010                             6,269,750
                     NR*      NR*      3,000,000  Pinnacle Polymers, Term, due 12/15/2006                         3,006,480
                     BB-      B1       4,000,000  Wellman, Inc., First Lien Term, due 2/04/2009                   3,928,332
                                                                                                             --------------
                                                                                                                 58,498,458

Consumer             BB-      Ba3      5,212,766  Josten's Inc., Term, due 7/29/2010                              5,269,455
Non-Durables--0.5%   NR*      NR*        845,805  Walls Industries, Term A, due 2/28/2006                            30,861
                                                                                                             --------------
                                                                                                                  5,300,316



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Schedule of Investments (continued)                                                       Master Senior Floating Rate Trust


                     S&P      Moody's  Face
Industry++           Rating   Rating   Amount     Senior Secured Floating Rate Loan Interests**                     Value
                                                                                              
Diversified          BB-      B1     $ 3,774,074  Dex Media, Inc., Term, due 3/09/2010                       $    3,831,078
Media--2.2%          B        B1       4,967,751  Liberty Group Operating, Term B, due 3/31/2007                  5,011,219
                     BB       Ba3      3,000,000  MediaNews Group, Inc., Term B, due 12/30/2010                   3,037,500
                     BB       Ba3      2,475,216  RH Donnelley, Term B, due 11/15/2009                            2,510,951
                     BB-      Ba2      1,461,290  Regal Cinema, Tranche B, due 6/30/2009                          1,481,535
                     B        Ba2      3,500,000  Six Flags Entertainment Corp., Term B, due 6/30/2009            3,545,938
                     BB+      Ba2      2,000,000  Vivendi, Term B, due 6/30/2008                                  2,015,938
                                                                                                             --------------
                                                                                                                 21,434,159

Energy--2.7%         BB+      Ba2      1,500,000  Citgo Petroleum Corp., Term B, due 2/27/2006                    1,560,000
                     BB+      Ba2      5,000,000  Cogentrix Delaware Holdings, Inc., Term B, due 2/27/2009        5,031,250
                     BB-      Ba3      1,006,451  Dresser, Inc., Term B, due 4/10/2009                            1,017,983
                     NR*      NR*      3,500,000  GulfTerra Energy Partners, L.P., Term, due 12/10/2008           3,530,625
                     B+       B2       2,500,000  Parker Drilling Company, Term, due 10/01/2007                   2,605,450
                     NR*      NR*      5,000,000  Pride International, Inc., Term B, due 1/15/2009                5,062,500
                     BB       Ba3      4,962,500  Tesoro Petroleum Corp., Term, due 4/15/2008                     5,119,647
                     NR*      NR*      2,674,424  WH Energy Services, Term B, due 4/16/2007                       2,701,168
                                                                                                             --------------
                                                                                                                 26,628,623

Food & Drug--0.5%    B+       B1       4,638,419  The Pantry Inc., Term, due 7/31/2006                            4,696,400

Food &               BB       Ba3        885,630  American Seafood, Term B, due 3/31/2009                           889,965
Tobacco--2.0%        BB+      Ba1      4,656,579  Dean Foods Company, Term B, due 7/30/2008                       4,732,248
                     BB-      Ba3      3,478,244  DelMonte, Term B, due 12/20/2010                                3,535,854
                                                  Doane Pet Care Company:
                     B-       B1       1,142,857      Revolving Credit, due 3/31/2005                             1,123,798
                     B-       B1         967,060      Term A, due 3/31/2005                                         969,477
                     B-       B1         698,187      Term B, due 12/31/2005                                        700,950
                     B+       B1       3,486,404  Domino's Pizza, Term, due 6/25/2010                             3,542,186
                     NR*      NR*      4,339,726  Dr. Pepper Bottling, Term B, due 12/19/2010                     4,407,534
                                                                                                             --------------
                                                                                                                 19,902,012

Gaming--2.0%         B+       Ba3      6,378,403  Ameristar Casinos Inc., Term B, due 12/31/2006                  6,417,273
                     B+       B2       5,386,500  Marina District Finance Co., Term B, due 12/13/2007             5,466,624
                     B        B2       3,920,000  Pinnacle Entertainment, Inc., Term, due 12/15/2009              3,952,928
                     B+       B1       2,955,000  Venetian Casino Resort, LLC/Las Vegas Sands, Inc.,
                                                  Term B, due 5/01/2008                                           3,001,787
                                                                                                             --------------
                                                                                                                 18,838,612

Health Care--3.3%    BB       B1       1,418,572  Alaris Medical Systems, Inc., Term, due 6/30/2009               1,435,772
                     BB-      Ba3      1,995,000  Community Health, Term, due 1/06/2011                           2,030,910
                     BB-      Ba3      6,464,983  Davita, Term B, due 3/31/2009                                   6,550,411
                     B+       B1       2,985,000  Kinetic Conc, Term B, due 8/11/2010                             3,029,775
                     BBB      Ba1      4,987,500  MedCo Health, Term B, due 6/30/2010                             5,066,337
                                                  Medical Specialties (d):
                     NR*      NR*     12,845,455      Axel, due 6/30/2004                                         3,211,364
                     NR*      NR*      4,418,182      Term, due 6/30/2001                                         1,104,545
                     B+       B1       4,209,005  MedPointe Inc., Term B, due 9/30/2008                           4,235,311
                     BB-      Ba3      2,500,000  Orthofix International NV, Term B, due 12/15/2008               2,520,312
                     BB+      Ba2      2,481,250  Oxford Health, Term, due 4/30/2009                              2,495,984
                                                                                                             --------------
                                                                                                                 31,680,721

Housing--0.7%        BB-      B1       4,477,500  Amsted Industries Incorporated, Term, due 10/15/2010            4,507,584
                     NR*      NR*      2,765,202  Trussway Industries Inc., Term B, due 12/31/2006                2,046,249
                                                                                                             --------------
                                                                                                                  6,553,833



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Schedule of Investments (continued)                                                       Master Senior Floating Rate Trust


                     S&P      Moody's  Face
Industry++           Rating   Rating   Amount     Senior Secured Floating Rate Loan Interests**                     Value
                                                                                              
Information          NR*      Ca     $ 1,507,923  Trend Technologies, Inc., Term, due 2/28/2007 (d)          $            0
Technology--0.0%

Leisure--3.0%                                     Wyndham International, Inc.:
                     NR*      NR*     12,991,174      Increasing Rate Term, due 4/01/2006                        12,680,308
                     NR*      NR*     16,497,466      Term, due 6/30/2006                                        16,266,204
                                                                                                             --------------
                                                                                                                 28,946,512

Manufacturing--1.3%                               ChannelMaster Holdings, Inc. (d):
                     NR*      NR*        128,199      Revolving Credit, due 11/15/2004                               53,202
                     NR*      NR*      3,287,072      Term, due 11/15/2004                                        1,164,037
                     NR*      Ba2      1,700,000  Goodman Manufacturing Company, LP, Term B, due 11/21/2009       1,722,313
                     BB+      Ba2      4,000,000  Roper Industries, Inc., 3.11% due 12/29/2008                    4,052,500
                     BBB-     Ba2      1,856,250  SPX Corporation, Term B, due 9/30/2009                          1,871,042
                     BB-      B1       3,486,457  Trimas Corporation, Term B, due 12/31/2009                      3,510,427
                                                                                                             --------------
                                                                                                                 12,373,521

Metals--Other--2.7%  B+       B1      13,051,250  Mueller Group, Term E, due 5/31/2008                           13,144,031
                     NR*      NR*     31,000,000  Ormet Corporation, Term, due 8/15/2008 (d)                     12,555,000
                                                                                                             --------------
                                                                                                                 25,699,031

Packaging--0.7%      B        B2       3,487,719  Graham Packaging Holdings Co., Term D, due 2/14/2010            3,526,084
                                                  Owens-Illinois Inc.:
                     BB       B1       1,500,000      Term A, due 4/01/2007                                       1,506,719
                     BB       B1       1,500,000      Term B, due 4/01/2008                                       1,512,969
                                                                                                             --------------
                                                                                                                  6,545,772

Paper--1.5%          BB+      Ba3      3,500,000  Georgia-Pacific Corporation, Term, due 11/28/2005               3,507,658
                     B+       B1       3,731,250  Graphic Packaging, Term B, due 8/08/2010                        3,791,107
                                                  Stone Container Corporation:
                     NR*      NR*      6,003,063      Term B, due 6/30/2009                                       6,083,102
                     NR*      NR*      1,017,118      Term C, due 6/30/2009                                       1,026,653
                                                                                                             --------------
                                                                                                                 14,408,520

Retail--0.9%         BB       Ba3      1,004,470  Advance Stores Company, Incorporated, Term E, due
                                                  11/30/2007                                                      1,016,712
                     B        B3       3,500,000  American Reprographics Company, LLC, Term, due 12/18/2009       3,552,500
                     B+       B1       3,800,000  General Nutrition Center, Inc., Term B, due 12/05/2009          3,826,125
                                                                                                             --------------
                                                                                                                  8,395,337

Service--4.5%        B        B1       3,253,886  Alliance Laundry Systems LLC, Term B, due 6/01/2007             3,268,799
                                                  Allied Waste Industries, Inc.:
                     BB       Ba3     10,495,714      Term, due 1/15/2010                                        10,675,013
                     BB       Ba3      3,571,429      Tranche A--Credit Linked Deposit, due 1/1/2010              3,629,782
                     NR*      C        8,122,491  Anthony Crane Rental Holdings LP, Term, due 7/20/2006           5,766,969
                     NR*      NR*      6,000,000  Buhrmann US Inc., Term B-1, due 12/23/2010                      6,087,186
                     BB-      Ba3      3,939,091  Corrections Corp. of America, Term C, due 3/31/2008             3,993,253
                                                  IT Group Inc. (d):
                     D        NR*      9,991,000      Term, due 6/08/2001                                           799,280
                     D        NR*      5,084,407      Term B, due 6/11/2006                                         406,753
                     NR*      Caa1     8,453,718  Prime Succession Inc., Term, due 8/01/2003 (d)                    338,149
                     BB-      Ba3      5,493,931  URS Corporation, Term B, due 7/01/2008                          5,512,819
                                                  United Rentals
                     BB       Ba3      2,444,444      Term, due 2/14/2011                                         2,475,929
                     BB       Ba3        666,667      Term B, due 2/14/2011                                         675,417
                                                                                                             --------------
                                                                                                                 43,629,349



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Schedule of Investments (continued)                                                       Master Senior Floating Rate Trust


                     S&P      Moody's  Face
Industry++           Rating   Rating   Amount     Senior Secured Floating Rate Loan Interests**                     Value
                                                                                              
Steel--1.2%          NR*      NR*    $ 9,503,264  Acme Metals Incorporated, Term, due 12/01/2005 (d)         $      451,405
                     BB+      Ba2      2,260,313  International Steel Group, Term A, due 5/07/2007                2,270,202
                                                  Ispat International:
                     B-       Caa1     4,774,024      Term B, due 7/15/2005                                       4,571,128
                     B-       Caa1     4,774,024      Term C, due 7/15/2005                                       4,571,128
                                                                                                             --------------
                                                                                                                 11,863,863

Telecommunications-- NR*      NR*      6,751,147  E. Spire Communication, Term C, due 8/11/2006 (d)                       1
1.6%                                              Intera:
                     NR*      NR*      2,586,301      Term A, due 12/31/2005                                        773,821
                     NR*      NR*        933,400      Term B, due 12/31/2005                                        279,273
                     NR*      NR*      1,803,542      Term C, due 12/31/2005                                        539,620
                                                  Transaction Network Services:
                     BB-      Ba3      2,670,817      Term B, due 4/03/2007                                       2,693,135
                     BB-      Ba3      3,145,309      Term B, due 3/31/2008                                       3,145,309
                     BB-      Ba3      7,944,134  Valor Telecommunications, Term B, due 6/30/2008                 8,003,715
                                                                                                             --------------
                                                                                                                 15,434,874

Transportation       BB+      Ba2      4,264,762  Kansas City Southern Railway Company, Term B, due
Services--1.3%                                    6/12/2008                                                       4,289,130
                     BB+      Ba3      1,940,000  Laidlaw International, Term B, due 6/30/2009                    1,975,566
                     B+       B1       4,150,000  North American Van Lines, Inc., Term, due 10/29/2010            4,187,611
                     BB-      B1       1,980,000  United Components, Inc., Term C, due 6/30/2010                  2,007,225
                                                                                                             --------------
                                                                                                                 12,459,532

Utilities--6.6%      BB       B2       2,000,000  The AES Corporation, Term, due 4/30/2008                        2,025,750
                                                  Aquila Networks Canada Corp.:
                     NR*      NR*      6,500,000      Term, due 7/31/2004                                         6,508,125
                     BB       B3       2,730,159      Term A, due 5/15/2006                                       2,821,163
                     NR*      NR*      2,000,000      Term A, due 7/31/2004                                       2,002,500
                                                  Calpine Corporation:
                     B        B1       6,965,000      Term, due 7/15/2007                                         6,647,222
                     B        B1       4,477,500      Term, due 7/16/2007                                         4,544,663
                                                  Mission Energy Holding Company:
                     CCC      Caa2     8,181,819      Term A, due 7/02/2006                                       7,936,363
                     CCC      Caa2    21,837,662      Term B, due 7/02/2006                                      21,182,533
                     CCC      Caa2     1,480,519      Term B, due 7/02/2007                                       1,436,104
                                                  NRG Energy, Inc.:
                     BB       B1         458,333      Credit Link Deposit, due 6/23/2010                            472,155
                     BB       B1         818,583      Term, due 6/23/2010                                           843,269
                     NR*      NR*      3,214,318  Reliant Resources, Inc., Term, due 3/15/2007                    3,155,390
                     BB+      Ba2      2,388,000  TNP Enterprises, Inc., Term, due 12/31/2006                     2,410,388
                     BB       B1       1,990,000  Williams Production RMT Company, Term, due 5/31/2007            2,007,413
                                                                                                             --------------
                                                                                                                 63,993,038

Wireless             B        B1      12,820,947  American Tower Systems Corp., Term B, due 12/31/2007           12,978,542
Communications--     B-       B2       4,300,000  Centennial, Term A, due 2/09/2011                               4,323,740
8.9%                                              Crown Castle Operating Company:
                     BB       Ba3     15,668,978      Term B, due 3/31/2008                                      15,978,001
                     B-       B1       3,500,000      Term B, due 9/30/2010                                       3,569,027
                     B        B1       4,488,750  Dobson Cellular Systems, Inc., Term, due 3/31/2010              4,532,035
                                                  Nextel Communications, Inc.:
                     BB       Ba2      1,842,105      Term A, due 12/31/2007                                      1,831,552
                     BB-      Ba2     32,000,000      Term E, due 12/15/2010                                     32,326,016
                     CCC+     B2       5,246,154  SBA Senior Finance, Inc., Term B, due 10/31/2008                5,256,114
                     B+       B1       5,657,288  Spectrasite Communications, Inc., Term, due 12/31/2007          5,730,527
                                                                                                             --------------
                                                                                                                 86,525,554

                                                  Total Investments in Senior Secured Floating Rate Loan
                                                  Interests (Cost--$831,614,892)--78.0%                         754,816,899



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Schedule of Investments (continued)                                                       Master Senior Floating Rate Trust


                     S&P      Moody's  Face
Industry++           Rating   Rating   Amount     Corporate Debt                                                    Value
                                                                                              
Chemicals--0.2%      NR*      NR*    $ 1,662,678  PCI Chemicals, Canada, 10% due 12/31/2008                  $    1,621,111
                     NR*      NR*        526,515  Pioneer Companies, Inc., 4.663% due 12/31/2006 (a)                513,352
                                                                                                             --------------
                                                                                                                  2,134,463

Telecommunications-- CCC+     B3       9,500,000  Qwest Communications International Inc., 4.63%
1.7%                                              due 2/15/2009 (a)(b)                                            8,977,500
                     B        B1       7,000,000  Time Warner Telecom Holdings, Inc., 5.12% due
                                                  2/15/2011 (a)(b)                                                6,947,500
                                                                                                             --------------
                                                                                                                 15,925,000

                                                  Total Investments in Corporate Debt
                                                  (Cost--$23,727,732)--1.9%                                      18,059,463



                                          Shares
                                            Held  Common Stocks
                                                                                                           
Chemicals--0.1%                          107,520  Pioneer Companies, Inc.                                           698,880

Metals & Mining--0.0%                     51,714  Acme Package Corp. Senior Holdings                                258,570

Telecommunications--0.0%                     839  Intera (Pacific Coin)                                                   0

                                                  Total Investments in Common Stocks (Cost--$693,424)--0.1%         957,450




                                                  Warrants (c)
                                                                                                    
Service--0.0%                             11,154  Anthony Crane Rental Holdings LP (Class A)                              0
                                           1,239  Anthony Crane Rental Holdings LP (Class L)                              0
                                                                                                             --------------
                                                                                                                          0

                                                  Total Investments in Warrants (Cost--$0)--0.0%                          0



                                      Beneficial
                                        Interest  Other Interests (e)
                                                                                                       
                                     $17,263,637  Medical Specialties Acquisition LLC                                   173
                                      17,263,637  Medical Specialties Mezzanine LLC                                     173
                                                                                                             --------------
                                                                                                                        346

                                          14,398  MEDIQ Incorporated (Preferred Stock Escrow due 4/01/2004)               0
                                          14,398  MEDIQ Incorporated (Preferred Stock Escrow due 2/01/2006)               0
                                                                                                             --------------
                                                                                                                          0

                                                  Total Investments in Other Interests (Cost--$0)--0.0%                 346



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Schedule of Investments (concluded)                                                       Master Senior Floating Rate Trust


                                      Beneficial
                                        Interest  Short-Term Securities                                             Value
                                                                                                       
                                    $189,349,206  Merrill Lynch Liquidity Series, LLC Cash Sweep
                                                  Series I***                                                $  189,349,206

                                                  Total Investments in Short-Term Securities
                                                  (Cost--$189,349,206)--19.6%                                   189,349,206

                     Total Investments (Cost--$1,045,385,254)--99.6%                                            963,183,364
                     Other Assets Less Liabilities--0.4%                                                          4,102,244
                                                                                                             --------------
                     Net Assets--100.0%                                                                      $  967,285,608
                                                                                                             ==============

(a)Floating rate note.

(b)The security may be offered and sold to "qualified institutional
buyers" under Rule 144A of the Securities Act of 1933.

(c)Warrants entitle the Trust to purchase a predetermined number of
shares of common stock and are non-income producing. The purchase
price and number of shares are subject to adjustment under certain
conditions until the expiration date.

(d)Non-income producing security.

(e)Other interests represent beneficial interest in liquidation
trusts and other reorganization entities and are non-income
producing.

*Not Rated.

**Senior secured floating rate loan interests in which the Trust
invests generally pay interest at rates that are periodically
redetermined by reference to a base lending rate plus a premium.
These base lending rates are generally (i) the lending rate offered
by one or more major European banks, such as LIBOR (London InterBank
Offered Rate), (ii) the prime rate offered by one or more major
United States banks or (iii) the certificate of deposit rate.

***Investments in companies considered to be an affiliate of the
Trust (such companies are defined as "Affiliated Companies" in
Section 2(a)(3) of the Investment Company Act of 1940) are as
follows:

                                           Net          Interest
Affiliate                                Activity        Income

Merrill Lynch Liquidity Series, LLC
   Cash Sweep Series I                 $116,874,886     $669,008


++For Trust compliance purposes, "Industry" means any one or more
of the industry sub-classifications used by one or more widely
recognized market indexes or ratings group indexes, and/or as
defined by Trust management. This definition may not apply for
purposes of this report, which may combine such industry sub-
classifications for reporting ease. Industries are shown as a
percent of net assets.

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Statement of Assets and Liabilities                                                       Master Senior Floating Rate Trust


As of February 29, 2004
                                                                                                   
Assets

               Investments, at value (identified cost--$1,045,385,254)                                      $   963,183,364
               Cash                                                                                                 333,875
               Receivables:
                  Interest (including $3,323 from affiliates)                             $     4,014,552
                  Securities sold                                                               2,932,078
                  Contributions                                                                 2,484,553
                  Commitment fees                                                                  18,724         9,449,907
                                                                                          ---------------
               Prepaid expenses and other assets                                                                     12,589
                                                                                                            ---------------
               Total assets                                                                                     972,979,735
                                                                                                            ---------------

Liabilities

               Payables:
                  Securities purchased                                                          5,025,000
                  Investment adviser                                                              625,137
                  Other affiliates                                                                  9,990         5,660,127
                                                                                          ---------------
               Accrued expenses and other liabilities                                                                34,000
                                                                                                            ---------------
               Total liabilities                                                                                  5,694,127
                                                                                                            ---------------

Net Assets

               Net assets                                                                                   $   967,285,608
                                                                                                            ===============

Net Assets Consist of

               Investors' capital                                                                           $ 1,049,487,498
               Unrealized depreciation on investments--net                                                     (82,201,890)
                                                                                                            ---------------
               Net Assets                                                                                   $   967,285,608
                                                                                                            ===============

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Statement of Operations                                                                   Master Senior Floating Rate Trust


For the Six Months Ended February 29, 2004
                                                                                                   
Investment Income

               Interest (including $669,008 from affiliates)                                                $    24,168,062
               Facility and other fees                                                                              436,715
                                                                                                            ---------------
               Total income                                                                                      24,604,777
                                                                                                            ---------------

Expenses

               Investment advisory fees                                                   $     4,423,680
               Accounting services                                                                149,980
               Professional fees                                                                   65,804
               Custodian fees                                                                      29,282
               Trustees' fees and expenses                                                         23,250
               Pricing fees                                                                         6,156
               Printing and shareholder reports                                                     2,451
               Other                                                                               10,406
                                                                                          ---------------
               Total expenses                                                                                     4,711,009
                                                                                                            ---------------
               Investment income--net                                                                            19,893,768
                                                                                                            ---------------

Realized & Unrealized Gain (Loss) on Investments--Net

               Realized loss on investments--net                                                               (34,074,589)
               Change in unrealized depreciation on investments--net                                             81,238,729
                                                                                                            ---------------
               Total realized and unrealized gain on investments--net                                            47,164,140
                                                                                                            ---------------
               Net Increase in Net Assets Resulting from Operations                                         $    67,057,908
                                                                                                            ===============

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Statements of Changes in Net Assets                                                       Master Senior Floating Rate Trust


                                                                                           For the Six           For the
                                                                                           Months Ended         Year Ended
                                                                                           February 29,         August 31,
Increase (Decrease) in Net Assets:                                                             2004                2003
                                                                                                   
Operations

               Investment income--net                                                     $    19,893,768   $    29,350,086
               Realized loss on investments--net                                             (34,074,589)      (14,781,467)
               Change in unrealized depreciation on investments--net                           81,238,729        67,910,155
                                                                                          ---------------   ---------------
               Net increase in net assets resulting from operations                            67,057,908        82,478,774
                                                                                          ---------------   ---------------

Capital Transactions

               Proceeds from contributions                                                     75,077,463        19,158,032
               Fair value of net assets contributions                                                  --       841,562,097
               Fair value of withdrawals                                                    (117,727,593)     (182,526,372)
                                                                                          ---------------   ---------------
               Net increase (decrease) in net assets derived from capital transactions       (42,650,130)       678,193,757
                                                                                          ---------------   ---------------

Net Assets

               Total increase in net assets                                                    24,407,778       760,672,531
               Beginning of period                                                            942,877,830       182,205,299
                                                                                          ---------------   ---------------
               End of period                                                              $   967,285,608   $   942,877,830
                                                                                          ===============   ===============

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Financial Highlights                                                                      Master Senior Floating Rate Trust

                                                                                                             For the Period
                                                                        For the Six                            October 6,
                                                                        Months Ended    For the Year Ended     2000++ to
The following ratios have been derived from                             February 29,        August 31,         August 31,
information provided in the financial statements.                           2004         2003          2002       2001
                                                                                                  
Total Investment Return**

               Total investment return                                      7.58%+++       11.07%      (4.66%)           --
                                                                          ==========   ==========   ==========   ==========


Ratios to Average Net Assets

               Expenses, excluding interest expense                           1.01%*        1.04%        1.09%       1.06%*
                                                                          ==========   ==========   ==========   ==========
               Expenses                                                       1.01%*        1.05%        1.12%       1.06%*
                                                                          ==========   ==========   ==========   ==========
               Investment income--net                                         4.26%*        4.80%        5.31%       7.92%*
                                                                          ==========   ==========   ==========   ==========

Leverage

               Amount of borrowings outstanding, end of period
               (in thousands)                                                     --           --   $   13,000           --
                                                                          ==========   ==========   ==========   ==========
               Average amount of borrowings outstanding during the
               period (in thousands)                                              --   $    3,187   $    3,959           --
                                                                          ==========   ==========   ==========   ==========

Supplemental Data

               Net assets, end of period (in thousands)                   $  967,286   $  942,878   $  182,205   $  376,931
                                                                          ==========   ==========   ==========   ==========
               Portfolio turnover                                             31.37%       56.56%       36.77%       19.53%
                                                                          ==========   ==========   ==========   ==========

*Annualized.

**Total investment return is required to be disclosed for fiscal
years beginning after December 15, 2000.

++Commencement of operations.

+++Aggregate total investment return.

See Notes to Financial Statements.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Notes to Financial Statements
Master Senior Floating Rate Trust


1. Significant Accounting Policies:
Master Senior Floating Rate Trust (the "Trust") is registered under
the Investment Company Act of 1940, as amended, and is organized as
a Delaware statutory trust. The Declaration of Trust permits the
Trustees to issue nontransferable interests in the Trust, subject to
certain limitations. The Trust's financial statements are prepared
in conformity with accounting principles generally accepted in the
United States of America, which may require the use of management
accruals and estimates. These unaudited financial statements reflect
all adjustments, which are, in the opinion of management, necessary
to a fair statement of the results for the interim period presented.
All such adjustments are of a normal, recurring nature. The
following is a summary of significant accounting policies followed
by the Trust.

(a) Loan participation interests--The Trust primarily invests in
senior secured floating rate loan interests ("Loan Interests") with
collateral having a market value, at the time of acquisition by the
Trust, which Trust management believes equals or exceeds the
principal amount of the Corporate Loan. The Trust may invest up to
20% of its total assets in loans made on an unsecured basis. Because
agents, banks and intermediate participants from whom the Trust
purchases the loan interest are primarily financial institutions,
the Trust's investment in Corporate Loans at February 29, 2004 could
be considered to be concentrated in the industry group consisting of
financial institutions.

(b) Valuation of investments--Loan Interests are valued in
accordance with guidelines established by the Board of Trustees.
Loan Interests are valued at the mean between the last available bid
and asked prices from one or more brokers or dealers as obtained
from Loan Pricing Corporation. For the limited number of Loan
Interests for which no reliable price quotes are available, such
Loan Interests will be valued by Loan Pricing Corporation through
the use of pricing matrices to determine valuations. If the pricing
service does not provide a value for the loan interests, the
Investment Adviser will value the Loan Interests at fair value,
which is intended to approximate market value.

Securities that are held by the Trust that are traded on stock
exchanges or the Nasdaq National Market are valued at the last sale
price or official close price on the exchange on which such
securities are traded, as of the close of business on the day the
securities are being valued or, lacking any sales, at the last
available bid price for long positions, and at the last available
ask price for short positions. In cases where securities are traded
on more than one exchange, the securities are valued on the exchange
designated as the primary market by or under the authority of the
Board of Trustees of the Trust. Long positions in securities traded
in the over-the-counter ("OTC") market, Nasdaq Small Cap or Bulletin
Board are valued at the last available bid price or yield equivalent
obtained from one or more dealers or pricing services approved by
the Board of Trustees of the Trust. Short positions in securities
traded in the OTC market are valued at the last available ask price.
Portfolio securities that are traded both in the OTC market and on a
stock exchange are valued according to the broadest and most
representative market. When the Trust writes an option, the amount
of the premium received is recorded on the books of the Trust as an
asset and an equivalent liability. The amount of the liability is
subsequently valued to reflect the current market value of the
option written, based on the last sale price in the case of exchange-
traded options or, in the case of options traded in the OTC market,
the last ask price. Options purchased by the Trust are valued at
their last sale price in the case of exchange-traded options or, in
the case of options traded in the OTC market, the last bid price.
The value of swaps, including interest rate swaps, caps and floors,
will be determined by obtaining dealer quotations. Other
investments, including futures contracts and related options, are
stated at market value. Obligations with remaining maturities of 60
days or less are valued at amortized cost unless the Investment
Adviser believes that this method no longer produces fair
valuations. Repurchase agreements will be valued at cost plus
accrued interest. The Trust employs certain pricing services to
provide securities prices for the Trust. Securities and assets for
which market quotations are not readily available are valued at fair
value as determined in good faith by or under the direction of the
Board of Trustees of the Trust, including valuations furnished by
the pricing services retained by the Trust, which may use a matrix
system for valuations. The procedures of a pricing service and its
valuations are reviewed by the officers of the Trust under the
general supervision of the Board of Trustees. Such valuations and
procedures will be reviewed periodically by the Trustees.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Notes to Financial Statements (continued)
Master Senior Floating Rate Trust


Generally, trading in foreign securities, as well as U.S. government
securities and money market instruments, is substantially completed
each day at various times prior to the close of business on the New
York Stock Exchange ("NYSE"). The values of such securities used in
computing the net assets of the Trust are determined as of such
times. Foreign currency exchange rates also are generally determined
prior to the close of business on the NYSE. Occasionally, events
affecting the values of such securities and such exchange rates may
occur between the times at which they are determined and the close
of business on the NYSE that may not be reflected in the computation
of the Trust's net assets. If events (for example, a company
announcement, market volatility or a natural disaster) occur during
such periods that are expected to materially affect the value of
such securities, those securities may be valued at their fair value
as determined in good faith by the Board of Trustees or by the
Investment Adviser using a pricing service and/or procedures
approved by the Board of Trustees.

(c) Derivative financial instruments--The Trust may engage in
various portfolio investment strategies both to increase the return
of the Trust and to hedge, or protect, its exposure to interest rate
movements and movements in the securities markets. Losses may arise
due to changes in the value of the contract or if the counterparty
does not perform under the contract.

* Swaps--The Trust may enter into swap agreements, which are over-
the-counter contracts in which the Trust and counterparty agree to
make periodic net payments on a specified notional amount. The net
payments can be made for a set period of time or may be triggered by
a pre-determined credit event. The net periodic payments may be
based on a fixed or variable interest rate; the change in market
value of a specified security, basket of securities, or index; or
the return generated by a security.

(d) Income taxes--The Trust is classified as a partnership for
Federal income tax purposes. As such, each investor in the Trust is
treated as owner of its proportionate share of the net assets,
income, expenses and realized and unrealized gains and losses of the
Trust. Therefore, no Federal income tax provision is required. It is
intended that the Trust's assets will be managed so an investor in
the Trust can satisfy the requirements of subchapter M of the
Internal Revenue Code.

(e) Security transactions and investment income--Security
transactions are recorded on the dates the transactions are entered
into (the trade dates). Realized gains and losses on security
transactions are determined on the identified cost basis. Dividend
income is recorded on the ex-dividend dates. Interest income is
recognized on the accrual basis. The Trust amortizes all premiums
and discounts on debt securities.


2. Investment Advisory Agreement and Transactions with Affiliates:
The Trust has entered into an Investment Advisory Agreement with
Fund Asset Management, L.P. ("FAM"). The general partner of FAM is
Princeton Services, Inc. ("PSI"), an indirect, wholly-owned
subsidiary of Merrill Lynch & Co., Inc. ("ML & Co."), which is the
limited partner.

FAM is responsible for the management of the Trust's portfolio and
provides the necessary personnel, facilities, equipment and certain
other services necessary to the operations of the Trust. For such
services, the Trust pays a monthly fee at an annual rate of .95% of
the average daily value of the Trust's net assets.

For the six months ended February 29, 2004, the Trust reimbursed FAM
$10,360 for certain accounting services.

Certain officers and/or trustees of the Trust are officers and/or
directors of FAM, PSI, FDS, and/or ML & Co.


3. Investments:
Purchases and sales of investments, excluding short-term securities,
for the six months ended February 29, 2004 were $253,221,131 and
$386,247,234, respectively.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Notes to Financial Statements (concluded)
Master Senior Floating Rate Trust


Net realized losses for the six months ended February 29, 2004 and
net unrealized losses as of February 29, 2004 were as follows:


                                 Realized         Unrealized
                                   Losses             Losses

Loan interests            $  (34,074,589)    $  (81,560,572)
Unfunded loan interests                --          (641,318)
                          ---------------    ---------------
Total                     $  (34,074,589)    $  (82,201,890)
                          ===============    ===============


As of February 29, 2004, net unrealized depreciation for Federal
income tax purposes aggregated $82,298,953, of which $10,741,698
related to appreciated securities and $93,040,651 related to
depreciated securities. At February 29, 2004, the aggregate cost of
investments for Federal income tax purposes was $1,045,482,317.


4. Unfunded Corporate Loans:
As of February 29, 2004, the Fund had unfunded loan commitments of
approximately $10,124,000, which would be extended at the option of
the borrower, pursuant to the following loan agreement:


                                                    Unfunded
                                                  Commitment
Borrower                                      (in thousands)

ChannelMaster Holdings, Inc.                      $  483,000
Doane Pet Care Company                            $3,143,000
Parker Drilling Company                           $2,500,000
Pinnacle Entertainment, Inc.                      $1,040,000
SBA Senior Finance, Inc.                          $  954,000
United Rentals, Inc.                              $  889,000
Walls Industries                                  $1,115,000


5. Short-Term Borrowings:
The Trust, along with certain other funds managed by FAM and its
affiliates, is a party to a $500,000,000 credit agreement with Bank
One, N.A. and certain other lenders. The Trust may borrow under the
credit agreement to fund investors, withdrawals and for other lawful
purposes other than for leverage. The Trust may borrow up to the
maximum amount allowable under the Trust's current prospectus and
statement of additional information, subject to various other legal,
regulatory or contractual limits. The Trust pays a commitment fee of
..09% per annum based on the Trust's pro rata share of the unused
portion of the credit agreement. Amounts borrowed under the credit
agreement bear interest at a rate equal to, at each fund's election,
the Federal Funds rate plus .50% or a base rate as determined by
Bank One, N.A. On November 28, 2003, the credit agreement was
renewed for one year under the same terms. The Fund did not
borrow under the credit agreement during the six months ended
February 29, 2004.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Portfolio Information
Master Senior Floating Rate Trust


As of February 29, 2004


                                        Percent of
Ten Largest Holdings                   Total Assets

Charter Communications Holdings*            6.3%
Century Cable Holdings LLC                  4.9
Huntsman International LLC*                 4.1
Nextel Communications, Inc.*                3.5
Mission Energy Holding Company*             3.1
Wyndham International, Inc.*                3.0
Olympus Cable Holdings LLC                  2.3
Crown Castle Operating Company*             2.0
Frontiervision Operating Partners LP*       2.0
CC VIII Operating Company LLC*              1.5

*Includes combined holdings and/or affiliates, where applicable.



                                        Percent of
Five Largest Industries++              Total Assets

Cable--U.S.                                22.6%
Wireless Communications                     8.9
Utilities                                   6.6
Chemicals                                   6.3
Service                                     4.5

++For Trust compliance purposes, "Industries" means any one or
more of the industry sub-classifications used by one or more widely
recognized market indexes or ratings group indexes, and/or as
defined by Trust management. This definition may not apply for
purposes of this report, which may combine such industry sub-
classifications for reporting ease.



                                        Percent of
Quality Ratings by                      Long-Term
S&P/Moody's                            Investments

BBB/Baa                                     2.6%
BB/Ba                                      37.5
B/B                                        38.5
CCC/Caa                                     7.5
CC/Ca and Lower                             0.9
NR (Not Rated)                             13.0



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Electronic Delivery


The Fund offers electronic delivery of communications to its
shareholders. In order to receive this service, you must
register your account and provide us with e-mail information.
To sign up for this service, simply access this website
http://www.icsdelivery.com/live and follow the instructions.
When you visit this site, you will obtain a personal identification
number (PIN). You will need this PIN should you wish to update your
e-mail address, choose to discontinue this service and/or make any
other changes to the service. This service is not available for
certain retirement accounts at this time.



MERRILL LYNCH SENIOR FLOATING RATE FUND, INC., FEBRUARY 29, 2004



Item 2 - Code of Ethics - Not Applicable to this semi-annual report

Item 3 - Audit Committee Financial Expert - Not Applicable to this
semi-annual report

Item 4 - Principal Accountant Fees and Services - Not Applicable to
this semi-annual report

Item 5 - Audit Committee of Listed Registrants - Not Applicable to
this semi-annual report

Item 6 - Schedule of Investments - Not Applicable

Item 7 - Disclosure of Proxy Voting Policies and Procedures for
Closed-End Management Investment Companies - Not Applicable to this
semi-annual report

Item 8 - Purchases of Equity Securities by Closed-End Management
Investment Company and Affiliated Purchasers - Not Applicable

Item 9 - Submission of Matters to a Vote of Security Holders - Not
Applicable

Item 10 - Controls and Procedures

10(a) - The registrant's certifying officers have reasonably
designed such disclosure controls and procedures to ensure material
information relating to the registrant is made known to us by others
particularly during the period in which this report is being
prepared.  The registrant's certifying officers have determined that
the registrant's disclosure controls and procedures are effective
based on our evaluation of these controls and procedures as of a
date within 90 days prior to the filing date of this report.

10(b) - There were no changes in the registrant's internal control
over financial reporting (as defined in Rule 30a-3(d) under the Act
(17 CFR 270.30a-3(d)) that occurred during the last fiscal half-year
of the period covered by this report that has materially affected,
or is reasonably likely to materially affect, the registrant's
internal control over financial reporting.

Item 11 - Exhibits attached hereto

11(a)(1) - Code of Ethics - Not Applicable to this semi-annual
report

11(a)(2) - Certifications - Attached hereto

11(a)(3) - Not Applicable

11(b) - Certifications - Attached hereto


Pursuant to the requirements of the Securities Exchange Act of 1934
and the Investment Company Act of 1940, the registrant has duly
caused this report to be signed on its behalf by the undersigned,
thereunto duly authorized.


Merrill Lynch Senior Floating Rate Fund, Inc.


By:    _/s/ Terry K. Glenn_______
       Terry K. Glenn,
       President of
       Merrill Lynch Senior Floating Rate Fund, Inc.


Date: April 16, 2004


Pursuant to the requirements of the Securities Exchange Act of 1934
and the Investment Company Act of 1940, this report has been signed
below by the following persons on behalf of the registrant and in
the capacities and on the dates indicated.


By:    _/s/ Terry K. Glenn________
       Terry K. Glenn,
       President of
       Merrill Lynch Senior Floating Rate Fund, Inc.


Date: April 16, 2004


By:    _/s/ Donald C. Burke________
       Donald C. Burke,
       Chief Financial Officer of
       Merrill Lynch Senior Floating Rate Fund, Inc.


Date: April 16, 2004