Morgan, Lewis & Bockius LLP
1111 Pennsylvania Avenue, NW
Washington, DC 20004
Tel:  202.739.3000
Fax:  202.739.3001
www.morganlewis.com



LAURA E. FLORES
202.739.5684
lflores@morganlewis.com


March 18, 2010


VIA EDGAR CORRESPONDENCE

Ms. Kimberly Browning
U.S. Securities and Exchange Commission
100 F Street, NE
Washington, DC  20549

Re:      RYDEX SERIES FUNDS (THE "TRUST") - POST EFFECTIVE AMENDMENT NO. 94
         ------------------------------------------------------------------
         (FILE NOS. 033-59692 AND 811-07584)
         -----------------------------------

Dear Ms. Browning:

This  letter  responds  to your  comments  conveyed  to us  during  a  telephone
conference  on March 11, 2010 relating to the Trust's  Post-Effective  Amendment
No. 94 ("PEA No. 94"),  filed on January 28, 2010 for the purpose of registering
a new share class,  Y-Class Shares, of the Managed Futures Strategy Fund and the
Long/Short   Commodities  Strategy  Fund.  This  letter  also  incorporates  the
comments,  to the extent they are applicable,  conveyed to us during a telephone
conference  on  February  23,  2010  regarding  Rydex ETF  Trust  Post-Effective
Amendment  No. 12 filed on December  18, 2009.  The  following  summarizes  your
comments,  and  our  responses  to  those  comments.   Unless  otherwise  noted,
capitalized  terms have the same meaning as  contained in the Fund's  Prospectus
and/or Statement of Additional Information ("SAI").

PROSPECTUS COMMENTS:
--------------------

1.       COMMENT.   Unless   permitted   by  Form   N-1A,   please   remove  all
         cross-references in Items 1 through 6.

         RESPONSE. We have revised Items 1 through 6 accordingly.

2.       COMMENT. Please delete the excess language from the Redemption Fee line
         item in each Fund's fees and expenses table  consistent  with Item 3 of
         Form N-1A.

         RESPONSE.   We  have  revised  each  Fund's  fees  and  expenses  table
         accordingly.

3.       COMMENT.  Please clarify in each Fund's "Principal Investment Strategy"
         disclosure the types of equity securities the Fund invests in.






         RESPONSE.  We have revised each Fund's "Principal  Investment Strategy"
         disclosure accordingly.

3.       COMMENT.  Please  revise each Fund's fees and expenses  table to delete
         the "Total  Other  Expenses"  line item and instead  disclose the total
         amount of Other  Expenses  opposite the "Other  Expenses" line item. In
         addition, please conform the "Net Total Annual Operating Expenses" line
         item description with Instruction 3(e) of Item 3.

         RESPONSE.   We  have  revised  each  Fund's  fees  and  expenses  table
         accordingly.

4.       COMMENT.  Please revise the last sentence of the "Example" narrative to
         replace "you" with "your."

         RESPONSE. We have revised each Fund's "Example" narrative accordingly.

5.       COMMENT.  Please  delete  the  last two  sentences  under  the  heading
         "Portfolio Turnover."

         RESPONSE.  We  respectfully  decline  to make  the  suggested  revision
         because  our  client  believes  that  the  disclosure  in the  last two
         sentences is necessary to ensure that shareholders fully understand the
         effect of each Fund's  investments in cash  instruments and derivatives
         on the portfolio turnover experienced by each Fund.

6.       COMMENT. In each Fund's "Principal Investment Strategy" section, please
         refrain from using equivocal terms in the  descriptions of the types of
         financial instruments and securities each Fund may invest in as part of
         its principal investment strategy.

         RESPONSE.  We have revised each Fund's "Principal  Investment Strategy"
         disclosure accordingly.

7.       COMMENT. Please confirm whether each Fund is an index fund. If they are
         not, please revise the Funds' fundamental  investment policy concerning
         industry   concentration   to   clarify   that  the   Funds'   industry
         concentration cannot float with an index. If the Funds are index funds,
         please  revise the last sentence of each Fund's  "Principal  Investment
         Strategy"  to reflect the  substance of the Funds'  fundamental  policy
         concerning issuer and industry concentration.

         RESPONSE.  We confirm  that both Funds are index funds and have revised
         the last  sentence of each Fund's  "Principal  Investment  Strategy" as
         follows (new language is in brackets):

         The Fund has adopted a  [fundamental]  investment  policy to not invest
         25% or more of the value of its assets in the securities of one or more
         issuers  conducting  their  principal  business  activities in the same
         industry[;  except that, to the extent the Fund's  underlying  index is
         concentrated  in a particular  industry,  the Fund will  necessarily be
         concentrated in that industry.]

8.       COMMENT. For Item 5 information, please use the prescribed headings set
         forth in Item 5.

         RESPONSE.  We have  revised  the  headings  for the Item 5  information
         accordingly.

9.       COMMENT.  Under the heading "More  Information About the Trust" and the
         sub-heading "Investment  Objectives," please confirm whether there is a
         policy to provide shareholder notice of a change in a Fund's investment
         objective. If so, please disclose such policy.






         RESPONSE.  Our client's  practice,  under normal  circumstances,  is to
         provide  60 days'  notice  prior to any  change of a Fund's  investment
         objective.  However,  in  cases  where  a Fund  is not  subject  to the
         requirements of Rule 35d-1,  our client has not adopted a formal policy
         to provide such notice and,  thus,  is unable to disclose such a policy
         in the Fund's prospectus.

10.      COMMENT.  Please confirm that all of the principal  risks  disclosed in
         Item 9 are summarized in Item 4 and vice versa.

         RESPONSE.  We confirm that all of the principal risks disclosed in Item
         9 are summarized in Item 4 and vice versa.

SAI COMMENTS:
-------------

11.      COMMENT.  Under the heading "Investment  Policies,  Techniques and Risk
         Factors" in the Funds' SAI, please  distinguish  between  principal and
         non-principal investment strategies.

         RESPONSE.  We believe the Funds' current  disclosure is consistent with
         the  requirements  of  Form  N-1A  and  therefore,   have  not  revised
         disclosure.  We,  however,  will  consider the staff's  suggestion  for
         future registration statements.

12.      COMMENT.   Please  confirm  that  each  of  the  principal  investments
         referenced under "Investment Policies, Techniques and Risk Factors" are
         disclosed in the Funds' Prospectus.

         RESPONSE. We confirm that each of the principal investments  referenced
         under "Investment Policies,  Techniques and Risk Factors" are disclosed
         in the Funds' Prospectus.

GENERAL COMMENT:
----------------

13.      COMMENT.  With respect to the Funds' fifth  non-fundamental  investment
         policy concerning pledging assets to secure borrowings,  please explain
         to the staff whether there is a percentage  limitation on the amount of
         assets  that may be  pledged  to secure  borrowings  in the  absence of
         having a segregated account.

         RESPONSE.  We have  confirmed  with our  client  that,  as a matter  of
         practice,  it does not pledge securities  without posting the requisite
         collateral in a segregated account. Therefore, it has not established a
         specific   percentage   limitation  that  it  would  pledge  without  a
         segregated account.

14.      COMMENT. PEA No. 94 was filed only under the Securities Act of 1933 and
         not the Investment Company Act of 1940. Please explain to the staff how
         you will correct this filing error.

         RESPONSE.  PEA No. 94 was  inadvertently not filed under the Investment
         Company  Act of 1940  due to an  EDGAR  submission  error.  Our  client
         intends  to file  another  post-effective  amendment  pursuant  to Rule
         485(a) to rectify the submission  error and to reflect the substance of
         the comments and responses set forth above as applicable.

                                       ***

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 me at 202.739.5684 or John McGuire at 202.739.5654.


Sincerely,

/s/ Laura E. Flores
-------------------
Laura E. Flores


c:  John McGuire, Esq.
    Amy Lee, Esq.
    Joanna Haigney