Morgan, Lewis & Bockius LLP
1111 Pennsylvania Ave., NW
Washington, DC 20004

LAURA E. FLORES
202.739.5684
lflores@morganlewis.com


  August 1, 2007


VIA EDGAR CORRESPONDENCE

Mr. Christian T. Sandoe
U.S. Securities and Exchange Commission
100 F Street, NE
Washington, DC  20549

Re:   RYDEX SERIES FUNDS (THE "TRUST") - POST-EFFECTIVE AMENDMENT ("PEA") NO. 70
      (FILE NOS. 33-59692 AND 811-07584)

Dear Mr. Sandoe:

This letter  responds to your comments to the Trust's  Post-Effective  Amendment
No.  70,  filed  on  May  25,  2007  for  the  purpose  of  reflecting  (i)  the
discontinuation  of the  master-feeder  arrangement  previously in place for the
Trust's Dynamic S&P 500,  Inverse Dynamic S&P 500,  Dynamic OTC, Inverse Dynamic
OTC, Dynamic Dow and Inverse Dynamic Dow Funds effective April 1, 2007; (ii) the
removal  of the  non-fundamental  investment  policy to invest at least 80% of a
Fund's net assets in a particular  investment  pursuant to Rule 35d-1 subject to
providing 60 days' notice to shareholders for certain series of the Trust; (iii)
a revised investment  strategy for the Absolute Return Strategies Fund; and (iv)
the reorganization of the prospectuses.  The following summarizes your comments,
and our response to those comments.  Unless otherwise noted,  capitalized  terms
have the same meaning as contained in the Fund's  Prospectuses  and/or Statement
of Additional Information ("SAI").

1.       COMMENT.  Please confirm that the Sector  Rotation  Fund's  investments
         will not be concentrated in any particular industry consistent with the
         Fund's fundamental policy concerning  concentration as disclosed in the
         SAI.

         RESPONSE.   Consistent  with  the  Sector  Fund's   fundamental  policy
         regarding  concentration,  the Fund will not  invest 25% or more of the
         value of the  Fund's  total  assets  in the  securities  of one or more
         issuers  conducting  their  principal  business  activities in the same
         industry.
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Mr. Christian T. Sandoe
August 1, 2007
Page 2

2.       COMMENT. Because Small and Mid-Capitalization Securities Risk is listed
         as a principal risk of the Sector  Rotation Fund,  consider  disclosing
         that the Fund invests in small and mid-capitalization securities in the
         Fund's investment strategy.

         RESPONSE.  Per your  suggestion,  we have  revised  the  second to last
         sentence of the Sector Rotation Fund's  investment  strategy as follows
         (new language  appears in bold for the purposes of this  correspondence
         only):

         "The Fund  invests in equity  securities,  INCLUDING  SMALL AND MID-CAP
         SECURITIES,  such as U.S. traded common stocks and American  Depository
         Receipts  ("ADRs"),  but may also invest in equity  derivatives such as
         futures contracts, options and swap agreements."

3.       COMMENT. Please confirm whether the Hedged Equity Fund's investments in
         equity  securities are hedged.  If they are not, please explain why the
         Fund's 80%  non-fundamental  investment policy adopted pursuant to Rule
         35d-1 is consistent with Rule 35d-1.

         RESPONSE.  We believe  that the Hedged  Equity  Fund's  non-fundamental
         investment  policy to invest at least 80% of its net  assets,  plus any
         borrowings for investment purposes, in long and short positions in U.S.
         and  foreign  equity  securities  of  any   capitalization   range,  or
         derivatives thereof,  including futures, options and swap agreements is
         consistent with Section 35(d) and Rule 35d-1 thereunder.  Foremost, the
         Fund's name is not materially  deceptive or misleading.  It is unlikely
         that the Fund's name would lead a reasonable  investor to conclude that
         the  Fund  invests  in  something  other  than  long and  short  equity
         positions or that the risks of those  investments are inconsistent with
         the risks typically associated with a hedging strategy involving equity
         securities.  In addition, the Fund's non-fundamental  investment policy
         to invest at least 80% of its assets in equity securities is consistent
         with  Rule  35d-1.  Rule  35d-1  requires  that a  non-fundamental  80%
         investment  policy  reference  the type of  investment  suggested  by a
         fund's name,  not terms  included in the fund's name that connote types
         of investment  strategies,  such as "growth" and "value."(1) Similar to
         "growth" and "value," the term "hedged" is  descriptive  and connotes a
         type of  investment  strategy,  not a type of  investment.  Because the
         Fund's name is not materially  deceptive or misleading,  and the Fund's
         non-fundamental  investment policy appropriately references the type of
         investment  suggested by the Fund's name,  both the Fund's name and its
         non-fundamental investment policy are consistent with Section 35(d) and
         Rule 35d-1 thereunder.

4.       COMMENT.  Please  disclose  whether the Real Estate  Companies that the
         Real   Estate   Fund   invests  in  are   primarily   engaged  in  real
         estate-related activities.
- ----------
(1) Final Rule: Investment Company Names, Rel. No. IC-24828 (Mar. 31, 2001).

                                       2


Mr. Christian T. Sandoe
August 1, 2007
Page 3

         RESPONSE. We have revised the fourth sentence of the Real Estate Fund's
         investment  strategy as follows (new  language  appears in bold for the
         purposes of this correspondence only):

         "Real Estate Companies, which also include master limited partnerships,
         are  PRIMARILY  engaged  in the  ownership,  construction,  management,
         financing  or  sale  of  residential,  commercial  or  industrial  real
         estate."

5.       COMMENT. Please consider making all references to a Fund plural in each
         risk discussion under "Description of Principal Risks."

         RESPONSE.  Because the singular use of "Fund" works well in conjunction
         with the risk matrix  included under  "Principal  Risks of Investing in
         the Funds," our client has decided not to make the suggested  change at
         this time, but will take it into consideration for future Prospectuses.

6.       COMMENT.  Please  confirm  that all Funds  that  invest  in  investment
         companies, including ETFs, include the required "Acquired Fund Fees and
         Expenses" line item in their respective fee tables.

         RESPONSE.  We have confirmed with our client that all Funds that invest
         in investment  companies and that incur related  expenses  greater than
         0.01% include the "Acquired  Fund Fees and Expenses" line item in their
         respective fee tables.

7.       COMMENT.  Please note that the Staff does not believe that inclusion of
         the term "strategy" in a Fund's name, other than a fund that invests in
         commodities,  is  sufficient  to remove the Fund from the scope of Rule
         35d-1 and the Rule's  requirement to have a non-fundamental  investment
         policy that provides that the Fund will invest 80% of its net assets in
         the type of investment suggested by the Fund's name.

         RESPONSE.  While we disagree  with the Staff's  decision to treat funds
         that invest in derivatives and similar  instruments to gain exposure to
         commodities  differently  from funds  that  invest in  derivatives  and
         similar instruments to gain exposure to other types of investments,  we
         have reincorporated the Funds'  non-fundamental  investment policies as
         previously adopted pursuant to Rule 35d-1.

8.       COMMENT.  Please consider  consolidating  the discussions of the Funds'
         frequent trading and redemption fee policies.

         RESPONSE.  As suggested,  we have deleted the section formerly entitled
         "Frequent  Trading and  Redemption  Fee Policy," and  consolidated  the
         information under "Frequent Purchases and Redemptions of Fund Shares."

9.       COMMENT.  Please consider  clarifying how the  responsibilities  differ
         between  the  three   portfolio   managers   listed  under   "Portfolio
         Management."

         RESPONSE. We have revised the second to last paragraph under "Portfolio
         Management"  as follows (new language  appears in bold for the purposes
         of this correspondence only):

                                       3


Mr. Christian T. Sandoe
August 1, 2007
Page 4

         "Mr.  Dellapa  oversees the RESEARCH AND creation of the processes used
         to select investments.  Mr. King oversees the day-to-day DETAILS OF THE
         PORTFOLIO  MANAGEMENT  of all of the Rydex Funds.  Mr. Byrum  generally
         oversees  ALL  ASPECTS  OF THE  MANAGEMENT  OF ALL THE RYDEX  FUNDS and
         reviews the  activities of Messrs.  King and Dellapa,  AS WELL AS OTHER
         ASPECTS OF THE INVESTMENT MANAGEMENT PORTFOLIO DEPARTMENT."

10.      COMMENT.  If the Funds provide Fund  information and  documentation  on
         their web site,  please  disclose this  information  under  "Additional
         Information."

         RESPONSE.  The  following  disclosure  is included  in the  "Additional
         Information" section:

         "You may obtain a copy of the SAI or the Annual or Semi-Annual Reports,
         without charge by calling  800.820.0888 or  301.296.5100,  visiting the
         Rydex web site at www.rydexinvestments.com,  or writing to Rydex Series
         Funds, at 9601 Blackwell Road, Suite 500, Rockville, Maryland 20850."

11.      COMMENT. If the Nova Fund invests in equity securities to a significant
         extent, please revise the investment strategy to so state.

         RESPONSE.  We believe that the existing disclosure adequately discloses
         the fact  that the Nova Fund will  invest  in  equity  securities  to a
         significant  extent.  Therefore,  we have not  revised  the  investment
         strategy as suggested.

12.      COMMENT.  Please  delete the word "may" in section  (ii) of the seventh
         fundamental  policy  included in the SAI,  and revise  section  (ii) to
         state that "a Sector Fund or the Real Estate Fund will be  concentrated
         in an industry or group of industries within a sector."

         RESPONSE.  We have  revised  section  (ii) of the  seventh  fundamental
         policy accordingly.

13.      COMMENT.  Please  clarify  the third  exception  in the Funds'  seventh
         fundamental policy concerning the concentration of Fund investments.

         RESPONSE.  We have  confirmed  with our  client  that  the  High  Yield
         Strategy Fund and Inverse High Yield  Strategy Fund will not invest 25%
         or more of the value of each Fund's total assets in the  securities  of
         one or more issuers conducting their principal  business  activities in
         the same  industry.  Therefore,  we have deleted  section  (iii) of the
         seventh fundamental policy.

14.      COMMENT.  Please  confirm  that the  Money  Market  Fund's  fundamental
         policies are consistent with the requirements set forth in Section 13.

         RESPONSE.  The Money Market Fund's fundamental  policies are consistent
         with the  requirements  set forth in Section 13 as  fundamental  policy
         numbers 9 through  17 are also  applicable  to the Money  Market  Fund.
         However,  to clarify the applicability of fundamental  policy numbers 9

                                       4


Mr. Christian T. Sandoe
August 1, 2007
Page 5

         through 17 to the Money Market  Fund,  we have revised the heading that
         precedes fundamental policy number 9 to reference the Money Market Fund
         as follows:

         "FUNDAMENTAL POLICIES OF THE INVERSE OTC STRATEGY FUND, INVERSE S&P 500
         STRATEGY FUND, NOVA FUND, OTC FUND,  PRECIOUS  METALS FUND,  GOVERNMENT
         LONG BOND 1.2X STRATEGY  FUND,  INVERSE  GOVERNMENT  LONG BOND STRATEGY
         FUND AND MONEY MARKET FUND"


                                       ***

I hereby acknowledge on behalf of Rydex Series Funds (the "Trust") that: (i) the
Trust is  responsible  for the adequacy and  accuracy of the  disclosure  in its
registration  statement;  (ii) SEC staff  comments or changes to  disclosure  in
response to staff comments in the registration  statement  reviewed by the staff
do not foreclose the SEC from taking any action with respect to the registration
statement; and (iii) the Trust may not assert SEC staff comments as a defense in
any proceeding  initiated by the SEC or any person under the federal  securities
laws of the United States.
                                       ***

If you have any  additional  questions  or  comments,  please do not hesitate to
contact either John McGuire at 202.739.5654 or me at 202.739.5684.

Sincerely,


/s/Laura E. Flores

Laura E. Flores

cc: Joanna M. Haigney
    W. John McGuire, Esq.