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: 811-03165

Active Assets Government Securities Trust
               (Exact name of registrant as specified in charter)

1221 Avenue of the Americas, New York, New York 10020
      (Address of principal executive offices)                        (Zip code)

Ronald E. Robison
1221 Avenue of the Americas, New York, New York 10020
                     (Name and address of agent for service)

Registrant's telephone number, including area code: 212-762-4000

Date of fiscal year end: June 30, 2004

Date of reporting period: December 31, 2003

Item 1 - Report to Shareholders


Welcome, Shareholder:

In this report, you'll learn about how your investment in Active Assets
Government Securities Trust performed during the semiannual period. We will
provide an overview of the market conditions, and discuss some of the factors
that affected performance during the reporting period. In addition, this report
includes the Fund's financial statements and a list of Fund investments.

This material must be preceded or accompanied by a prospectus for the fund being
offered. Market forecasts provided in this report may not necessarily come to
pass. There is no assurance that the Fund will achieve its investment objective.
The Fund is subject to market risk, which is the possibility that market values
of securities owned by the Fund will decline and, therefore, the value of the
Fund's shares may be less than what you paid for them. Accordingly, you can lose
money investing in this Fund.


FUND REPORT

For the six-month period ended December 31, 2003

MARKET CONDITIONS


The Federal Open Market Committee (the "Fed") lowered its target rate for
federal funds to 1.00 percent, a 45-year low, on June 25, 2003. It maintained
that target throughout the second half of the year to encourage a faster pace of
economic activity. By the second half of 2003 the combination of this highly
accommodative monetary posture and stimulative fiscal policies in the form of
tax cuts appeared to begin to have an effect, with many companies reporting
improved second-half earnings and the third-quarter GDP increasing to 8.2
percent. The Fed's sustained emphasis on low interest rates had a marked impact
on money market fund yields, which reached record low levels during the period.

PERFORMANCE ANALYSIS


As of December 31, 2003, Active Assets Government Securities Trust had net
assets of approximately $1.22 billion and the average maturity of the Fund's
portfolio was 42 days. For the six-month period ended December 31, 2003, the
Fund returned 0.25 percent. For the seven-day period ended December 31, 2003,
the Fund provided an effective annualized yield and a current yield both of 0.50
percent, while its 30-day moving average yield for December was 0.51 percent.
Past performance is no guarantee of future results.

Our strategy in managing the Fund remained consistent with our long-term focus
on maintaining preservation of capital and very high liquidity.* As we have in
the past, we adhered to a conservative approach that avoided the use of
derivatives or structured notes that might fluctuate excessively with changing
interest rates. On December 31, 2003, approximately 96 percent of the Fund's
portfolio was invested in federal agency discount notes with the remaining 4
percent in a U.S. Treasury obligation. At the end of the fiscal period,
approximately 96 percent of the Fund's holdings were due to mature in less than
four months.

- ----------------------------------------------------
*  An investment in the Fund is not insured or guaranteed by the Federal Deposit
   Insurance Corporation or any other government agency. Although the Fund seeks
   to preserve the value of your investment at $1.00 per share, it is possible
   to lose money by investing in the Fund.

2


<Table>
<Caption>
   PORTFOLIO COMPOSITION
                                                 
   U.S. Government Agencies                            95.9%
   U.S. Treasury Bill                                   4.1
</Table>

<Table>
<Caption>
   MATURITY SCHEDULE
                                                 
    1 - 30 Days                                        43.6%
    31 - 60 Days                                       31.9
    61 - 90 Days                                       14.7
    91 - 120 Days                                       5.7
   121+ Days                                            4.1
</Table>

Subject to change daily. All percentages are as a percentage of total
investments. Provided for informational purposes only and should not be deemed
as a recommendation to buy or sell the securities mentioned. Morgan Stanley is a
full-service securities firm engaged in securities trading and brokerage
activities, investment banking, research and analysis, financing and financial
advisory services.

INVESTMENT STRATEGY


1) THE FUND WILL INVEST IN HIGH QUALITY, SHORT-TERM U.S. GOVERNMENT SECURITIES.

2) THE FUND'S "INVESTMENT MANAGER," MORGAN STANLEY INVESTMENT ADVISORS INC.,
   SEEKS TO MAINTAIN THE FUND'S SHARE PRICE AT $1.00. THE SHARE PRICE REMAINING
   STABLE AT $1.00 MEANS THAT THE FUND WOULD PRESERVE THE PRINCIPAL VALUE OF
   YOUR INVESTMENT.

                                                                               3


Active Assets Government Securities Trust
PORTFOLIO OF INVESTMENTS - DECEMBER 31, 2003 (UNAUDITED)

<Table>
<Caption>
                                                                          ANNUALIZED
PRINCIPAL                           DESCRIPTION                              YIELD
AMOUNT IN                               AND                               ON DATE OF
THOUSANDS                          MATURITY DATES                          PURCHASE          VALUE
- -------------------------------------------------------------------------------------------------------
                                                                               
            U.S. Government Agencies (95.8%)
$766,750    Federal Home Loan Banks
              01/02/04 - 03/19/04.......................................  0.65 - 1.07%  $  766,079,477
 285,000    Federal National Mortgage Assoc.
              01/07/04 - 03/17/04.......................................  1.06 - 1.10      284,690,373
 120,000    Freddie Mac
              02/12/04 - 04/15/04.......................................  1.08 - 1.10      119,722,194
                                                                                        --------------
            Total U.S. Government Agencies (Cost $1,170,492,044).....................    1,170,492,044
                                                                                        --------------
            U.S. Government Obligation (4.1%)
  50,000    U.S. Treasury Bill 05/20/04
              (Cost $49,802,639)........................................     1.02           49,802,639
                                                                                        --------------
</Table>

<Table>
                                                                                     
            Total Investments (Cost $1,220,294,683) (a)....................    99.9%           1,220,294,683

            Other Assets in Excess of Liabilities..........................     0.1                  659,431
                                                                              -----           --------------
            Net Assets.....................................................   100.0%          $1,220,954,114
                                                                              =====           ==============
</Table>

- ---------------------

<Table>
  
(a)  Cost is the same for federal income tax purposes.
</Table>

4
                       See Notes to Financial Statements


Active Assets Government Securities Trust
FINANCIAL STATEMENTS

Statement of Assets and Liabilities
December 31, 2003 (unaudited)

<Table>
                                                           
Assets:
Investments in securities, at value (cost $1,220,294,683)...  $1,220,294,683
Cash........................................................          20,205
Receivable for shares of beneficial interest sold...........       1,339,728
Prepaid expenses and other assets...........................          26,685
                                                              --------------
    Total Assets............................................   1,221,681,301
                                                              --------------
Liabilities:
Payable for:
    Investment management fee...............................         507,068
    Distribution fee........................................         119,116
Accrued expenses and other payables.........................         101,003
                                                              --------------
    Total Liabilities.......................................         727,187
                                                              --------------
    Net Assets..............................................  $1,220,954,114
                                                              ==============
Composition of Net Assets:
Paid-in-capital.............................................  $1,220,909,175
Accumulated undistributed net investment income.............          44,939
                                                              --------------
    Net Assets..............................................  $1,220,954,114
                                                              ==============
Net Asset Value Per Share,
1,220,953,480 shares outstanding (unlimited shares
authorized of $.01 par value)...............................           $1.00
                                                              ==============
</Table>

                                                                               5
                       See Notes to Financial Statements


Active Assets Government Securities Trust
FINANCIAL STATEMENTS continued

Statement of Operations
For the six months ended December 31, 2003 (unaudited)

<Table>
                                                           
Net Investment Income:
Interest Income.............................................  $6,979,800
                                                              ----------
Expenses
Investment management fee...................................   2,819,821
Distribution fee............................................     662,025
Transfer agent fees and expenses............................      65,584
Registration fees...........................................      35,387
Custodian fees..............................................      29,683
Professional fees...........................................      22,829
Shareholder reports and notices.............................      21,656
Trustees' fees and expenses.................................      10,827
Other.......................................................      14,277
                                                              ----------
    Total Expenses..........................................   3,682,089
                                                              ----------
Net Investment Income.......................................  $3,297,711
                                                              ==========
</Table>

6
                       See Notes to Financial Statements


Active Assets Government Securities Trust
FINANCIAL STATEMENTS continued

Statement of Changes in Net Assets

<Table>
<Caption>
                                                                 FOR THE SIX       FOR THE YEAR
                                                                MONTHS ENDED          ENDED
                                                              DECEMBER 31, 2003   JUNE 30, 2003
                                                              -----------------   --------------
                                                                 (unaudited)
                                                                            
Increase (Decrease) in Net Assets:
Operations:
Net investment income.......................................   $    3,297,711     $   13,801,455
Net realized gain...........................................               --              1,458
                                                               --------------     --------------
    Net Increase............................................        3,297,711         13,802,913
                                                               --------------     --------------
Dividends and Distributions to Shareholders from:
Net investment income.......................................       (3,297,615)       (13,801,110)
Net realized gain...........................................               --             (1,458)
                                                               --------------     --------------
    Total Dividends and Distributions.......................       (3,297,615)       (13,802,568)
                                                               --------------     --------------

Net decrease from transactions in shares of beneficial
  interest..................................................       (7,739,740)      (198,302,159)
                                                               --------------     --------------
    Net Decrease............................................       (7,739,644)      (198,301,814)
Net Assets:
Beginning of period.........................................    1,228,693,758      1,426,995,572
                                                               --------------     --------------
End of Period
(Including accumulated undistributed net investment income
of $44,939 and $44,843, respectively).......................   $1,220,954,114     $1,228,693,758
                                                               ==============     ==============
</Table>

                                                                               7
                       See Notes to Financial Statements


Active Assets Government Securities Trust
NOTES TO FINANCIAL STATEMENTS - DECEMBER 31, 2003 (UNAUDITED)

1. Organization and Accounting Policies

Active Assets Government Securities Trust (the "Fund") is registered under the
Investment Company Act of 1940, as amended (the "Act"), as a diversified,
open-end management investment company. The Fund's investment objectives are
high current income, preservation of capital and liquidity. The Fund was
organized as a Massachusetts business trust on March 30, 1981 and commenced
operations on July 7, 1981.

The following is a summary of significant accounting policies:

A. Valuation of Investments -- Portfolio securities are valued at amortized
cost, which approximates market value.

B. Accounting for Investments -- Security transactions are accounted for on the
trade date (date the order to buy or sell is executed). Realized gains and
losses on security transactions are determined by the identified cost method.
Discounts are accreted and premiums are amortized over the life of the
respective securities. Interest income is accrued daily.

C. Repurchase Agreements -- The Fund may invest directly with institutions in
repurchase agreements. The Fund's custodian receives the collateral, which is
marked-to-market daily to determine that the value of the collateral does not
decrease below the repurchase price plus accrued interest.

D. Federal Income Tax Policy -- 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 its
shareholders. Accordingly, no federal income tax provision is required.

E. Dividends and Distributions to Shareholders -- The Fund records dividends and
distributions to shareholders as of the close of each business day.

F. Use of Estimates -- The preparation of financial statements in accordance
with generally accepted accounting principles requires management to make
estimates and assumptions that affect the reported amounts and disclosures.
Actual results could differ from those estimates.

2. Investment Management Agreement

Pursuant to an Investment Management Agreement with Morgan Stanley Investment
Advisors Inc. (the "Investment Manager"), the Fund pays the Investment Manager a
management fee, accrued daily and payable monthly, by applying the following
annual rates to the net assets of the Fund determined as of the close of each
business day: 0.50% to the portion of daily net assets not exceeding

8


Active Assets Government Securities Trust
NOTES TO FINANCIAL STATEMENTS - DECEMBER 31, 2003 (UNAUDITED) continued

$500 million; 0.425% to the portion of daily net assets exceeding $500 million
but not exceeding $750 million; 0.375% to the portion of daily net assets
exceeding $750 million but not exceeding $1 billion; 0.35% to the portion of
daily net assets exceeding $1 billion but not exceeding $1.5 billion; 0.325% to
the portion of daily net assets exceeding $1.5 billion but not exceeding $2
billion; 0.30% to the portion of daily net assets exceeding $2 billion but not
exceeding $2.5 billion; 0.275% to the portion of daily net assets exceeding $2.5
billion but not exceeding $3 billion; and 0.25% to the portion of daily net
assets exceeding $3 billion.

3. Plan of Distribution

Morgan Stanley Distributors Inc. (the "Distributor"), an affiliate of the
Investment Manager, is the distributor of the Fund's shares and in accordance
with a Plan of Distribution (the "Plan") pursuant to Rule 12b-1 under the Act,
finances certain expenses in connection with the promotion of sales of Fund
shares.

Reimbursements for these expenses are made in monthly payments by the Fund to
the Distributor, which will in no event exceed an amount equal to a payment at
the annual rate of 0.15% of the Fund's average daily net assets during the
month. Expenses incurred by the Distributor pursuant to the Plan in any fiscal
year will not be reimbursed by the Fund through payments accrued in any
subsequent fiscal year. For the six months ended December 31, 2003, the
distribution fee was accrued at the annual rate of 0.10%.

4. Security Transactions and Transactions with Affiliates

The cost of purchases and proceeds from sales/maturities of portfolio securities
for the six months ended December 31, 2003, aggregated $20,007,143,517 and
$20,022,453,677, respectively.

Morgan Stanley Trust, an affiliate of the Investment Manager and Distributor, is
the Fund's transfer agent. At December 31, 2003, the Fund had transfer agent
fees and expenses payable of approximately $1,300.

The Fund has an unfunded noncontributory defined benefit pension plan covering
certain independent Trustees of the Fund who will have served as independent
Trustees for at least five years at the time of retirement. Benefits under this
plan are based on factors which include years of service and compensation.
Aggregate pension costs for the six months ended December 31, 2003, included in
Trustees' fees and expenses in the Statement of Operations amounted to $3,674.
At December 31, 2003, the Fund had an accrued pension liability of $60,304 which
is included in accrued expenses in the Statement of Assets and Liabilities.

                                                                               9


Active Assets Government Securities Trust
NOTES TO FINANCIAL STATEMENTS - DECEMBER 31, 2003 (UNAUDITED) continued

On December 2, 2003, the Trustees voted to close the plan to new participants,
eliminate the future benefits growth due to increases to compensation after July
31, 2003 and effective April 1, 2004, establish an unfunded deferred
compensation plan which allows each independent Trustee to defer payment of all
or a portion of the fees he receives for serving on the Board of Trustees
throughout the year.

5. Shares of Beneficial Interest

Transactions in shares of beneficial interest, at $1.00 per share, were as
follows:

<Table>
<Caption>
                                                                 FOR THE SIX       FOR THE YEAR
                                                                MONTHS ENDED          ENDED
                                                              DECEMBER 31, 2003   JUNE 30, 2003
                                                              -----------------   --------------
                                                                 (unaudited)
                                                                            

Shares sold.................................................    3,180,778,452      6,396,600,275
Shares issued in reinvestment of dividends and
  distributions.............................................        3,291,368         13,784,355
                                                               --------------     --------------
                                                                3,184,069,820      6,410,384,630
Shares redeemed.............................................   (3,191,809,560)    (6,608,686,789)
                                                               --------------     --------------
Net decrease in shares outstanding..........................       (7,739,740)      (198,302,159)
                                                               ==============     ==============
</Table>

6. Legal Matters

The Investment Manager, certain affiliates of the Investment Manager and certain
investment companies advised by the Investment Manager or its affiliates,
including the Fund, are named as defendants in a number of recently filed,
similar class action complaints. These complaints generally allege that
defendants, including the Fund, violated their statutory disclosure obligations
and fiduciary duties by failing properly to disclose (i) that the Investment
Manager and certain affiliates of the Investment Manager allegedly offered
economic incentives to brokers and others to steer investors to the funds
advised by the Investment Manager or its affiliates rather than funds managed by
other companies, and (ii) that the funds advised by the Investment Manager or
its affiliates, including the Fund, allegedly paid excessive commissions to
brokers in return for their alleged efforts to steer investors to these funds.
The complaints seek, among other things, unspecified compensatory damages,
rescissionary damages, fees and costs. The defendants intend to move to dismiss
these actions and otherwise vigorously to defend them. While the Fund believes
that it has meritorious defenses, the ultimate outcome of these matters is not
presently determinable at this early stage of the litigation, and no provision
has been made in the Fund's financial statements for the effect, if any, of
these matters.

10


Active Assets Government Securities Trust
FINANCIAL HIGHLIGHTS

Selected ratios and per share data for a share of beneficial interest
outstanding throughout each period:

<Table>
<Caption>
                                      FOR THE SIX                        FOR THE YEAR ENDED JUNE 30,
                                     MONTHS ENDED      ---------------------------------------------------------------
                                   DECEMBER 31, 2003      2003          2002          2001         2000        1999
                                   -----------------   -----------   -----------   -----------   ---------   ---------
                                      (unaudited)
                                                                                           
Selected Per Share Data:

Net asset value, beginning of
 period..........................        $  1.00          $  1.00       $  1.00       $  1.00      $ 1.00      $ 1.00
                                         -------          -------       -------       -------      ------      ------

Net income from investment
 operations......................          0.003            0.009         0.020         0.053       0.050       0.045

Less dividends from net
 investment income...............         (0.003)          (0.009)+      (0.020)+      (0.053)     (0.050)     (0.045)
                                         -------          -------       -------       -------      ------      ------

Net asset value, end of period...        $  1.00          $  1.00       $  1.00       $  1.00      $ 1.00      $ 1.00
                                         =======          =======       =======       =======      ======      ======

Total Return.....................           0.25%(1)         0.95%         2.01%         5.48%       5.17%       4.64%

Ratios to Average Net Assets:
Expenses.........................           0.56%(2)         0.55%         0.53%         0.56%       0.59%       0.61%

Net investment income............           0.50%(2)         0.96%         1.96%         5.24%       5.03%       4.50%

Supplemental Data:
Net assets, end of period, in
 millions........................         $1,221           $1,229        $1,427        $1,603        $932        $995
</Table>

- ---------------------

<Table>
  
 +   Includes capital gain distribution of less than $0.001.
(1)  Not annualized.
(2)  Annualized.
</Table>

                       See Notes to Financial Statements

                                                                              11


TRUSTEES

Michael Bozic
Charles A. Fiumefreddo
Edwin J. Garn
Wayne E. Hedien
James F. Higgins
Dr. Manuel H. Johnson
Joseph J. Kearns
Michael E. Nugent
Philip J. Purcell
Fergus Reid

OFFICERS

Charles A. Fiumefreddo
Chairman of the Board

Mitchell M. Merin
President

Ronald E. Robison
Executive Vice President and Principal Executive Officer

Barry Fink
Vice President and General Counsel

Joseph J. McAlinden
Vice President

Stefanie V. Chang
Vice President

Francis J. Smith
Treasurer and Chief Financial Officer

Thomas F. Caloia
Vice President

Mary E. Mullin
Secretary

TRANSFER AGENT

Morgan Stanley Trust
Harborside Financial Center, Plaza Two
Jersey City, New Jersey 07311

INDEPENDENT AUDITORS

Deloitte & Touche LLP
Two World Financial Center
New York, New York 10281

INVESTMENT ADVISOR

Morgan Stanley Investment Advisors Inc.
1221 Avenue of the Americas
New York, New York 10020

The financial statements included herein have been taken from the records of the
Fund without examination by the independent auditors and accordingly they do not
express an opinion thereon.

This report is submitted for the general information of shareholders of the
Fund. Fore more detailed information about the Fund, its fees and expenses and
other pertinent information, please read its Prospectus. The Fund's Statement of
Additional Information contains additional information about the Fund, including
its trustees. It is available, without charge, by calling (800) 869-NEWS.

This report is not authorized for distribution to prospective investors in the
Fund unless preceded or accompanied by an effective Prospectus. Read the
Prospectus carefully before investing.

Investments and services offered through Morgan Stanley DW Inc., member SIPC.
Morgan Stanley Distributors Inc., member NASD.

(c) 2003 Morgan Stanley

[MORGAN STANLEY LOGO]

MORGAN STANLEY FUNDS

Active Assets
Government
Securities Trust

Semiannual Report
December 31, 2003

[MORGAN STANLEY LOGO]

13677B04-AP-2/04


Item 2. Code of Ethics.

Not applicable for semiannual reports.

Item 3. Audit Committee Financial Expert.

Not applicable for semiannual reports.

Item 4. Principal Accountant Fees and Services

Not applicable for semiannual reports.

Item 5. Audit Committee of Listed Registrants.

Not applicable for semiannual reports.

Item 6. [Reserved.]

Item 7.  Disclosure  of Proxy Voting  Policies  and  Procedures  for  Closed-End
Management Investment Companies.

Not applicable for semiannual reports.

Item 8. [Reserved.]

Item 9 - Controls and Procedures

(a) The Fund's principal executive officer and principal financial officer have
concluded that the Fund's disclosure controls and procedures are sufficient to
ensure that information required to be disclosed by the Fund in this Form N-CSR
was recorded, processed, summarized and reported within the time periods
specified in the Securities and Exchange Commission's rules and forms, based
upon such officers' evaluation of these controls and procedures as of a date
within 90 days of the filing date of the report.

  There were no significant changes or corrective actions with regard to
significant deficiencies or material weaknesses in the Fund's internal controls
or in other factors that could significantly affect the Fund's internal controls
subsequent to the date of their evaluation.



(b) There were no changes in the registrant's internal control over financial
reporting that occurred during the registrant's most recent fiscal half-year
(the registrant's second fiscal half-year in the case of an annual report) that
has materially affected, or is reasonably likely to materially affect, the
registrant's internal control over financial reporting.

Item 10 Exhibits

(a) Code of Ethics - Not applicable for semiannual reports.

(b) A separate certification for each principal executive officer and principal
financial officer of the registrant are attached hereto as part of EX-99.CERT.

                                        2



                                   SIGNATURES

         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.

Active Assets Government Securities Trust

/s/ Ronald E. Robison
Ronald E. Robison
Principal Executive Officer
February 18, 2004

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

/s/ Ronald E. Robison
Ronald E. Robison
Principal Executive Officer
February 18, 2004

/s/ Francis Smith
Francis Smith
Principal Financial Officer
February 18, 2004

                                        3