[Janus Letterhead]

October 7, 2008

VIA EDGAR

Mr. Larry Greene
Division of Investment Management
U.S. Securities and Exchange Commission
100 F Street, N.E.
Washington, DC 20549-0505

Re:  JANUS ADVISER SERIES (the "Registrant")
     1933 Act File No. 333-33978
     1940 Act File No. 811-09885
     Post-Effective Amendment No. 45

Dear Mr. Greene:

On behalf of the Registrant and Janus Adviser Modular Portfolio Construction
Fund (the "Fund"), this letter is to respond to your comments made by telephone
on August 20, 2008 with respect to the Registrant's Post-Effective Amendment No.
45 filed pursuant to Rule 485(a) under the Securities Act of 1933, as amended,
(the "1933 Act") on June 20, 2008. The Staff of the Securities and Exchange
Commission's (the "Staff") comments and the Registrant's responses to Staff
comments are as follows:

1.   COMMENT: The Staff requested that the Registrant reflect in writing all
     comments and responses and carry over comments, as applicable, to the
     Registrant's other Prospectuses and Statements of Additional Information
     ("SAIs").

     RESPONSE: The Registrant acknowledges the comment and confirms that it has
     complied.

2.   COMMENT: The Staff questioned whether or not the Fund's ability to invest
     directly in individual securities in addition to other Janus mutual funds
     was allowed under Section 12(d)(1)(G) of the Investment Company Act of
     1940, as amended, (the "1940 Act") or if the Registrant is relying on an
     exemptive order.

     RESPONSE: The Registrant believes that the Fund's strategies are consistent
     with and allowed under Rule 12d1-2 (the new "fund of funds rules"). The
     rule allows investment companies that rely on Section 12(d)(1)(G) to not
     only invest in affiliated investment companies in addition to Government
     securities and short-term paper, but to also invest in securities issued by
     other unaffiliated investment companies as well as securities other than
     those issued by an investment company.

3.   COMMENT: With respect to disclosure describing the Fund's "Alpha category,"
     the Staff asked for more specificity regarding what type of investments
     would be considered in the Alpha category.

     RESPONSE: The Registrant acknowledges the comment and believes the
     referenced disclosure has been updated appropriately. As presented in the
     Risk/Return Summary for the Fund, the Alpha category is comprised of
     underlying funds that invest in a broad range of traditional asset classes
     (which include equity and fixed income investments such as large-, mid-,
     and small-cap stocks, emerging market



     stocks, investment grade bonds, and high-yield bonds). The Alpha category
     is less focused on the asset class composition of the global market.

4.   COMMENT: The Staff noted that, to the extent the Fund intends to invest in
     real estate securities, the Registrant should ensure that appropriate risk
     disclosure be included in the Fund's prospectuses.

     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure has been included. In the event that the Fund
     increases its investment in real estate securities, the Registrant will
     re-evaluate the appropriateness of the applicable risk disclosure.

5.   COMMENT: With respect to statements indicating the Fund may invest in
     emerging markets and fixed-income instruments, the Staff noted that
     appropriate corresponding risk disclosure should be included in the Fund's
     prospectuses.

     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure has been included.

6.   COMMENT: The Staff requested clarity regarding what was intended by the
     statement that the Fund's "alternative strategy" could include leveraged
     securities.

     RESPONSE: The Registrant has updated the referenced disclosure by removing
     the term "leveraged securities." The disclosure now states that a part of
     the Fund's alternative strategy is the Fund's investment in "other
     securities less correlated to the market."

7.   COMMENT: The Staff suggested that, as a part of the Fund's Item 2 of Form
     N-1A disclosure, the Registrant clarify how the underlying funds listed in
     Appendix A ("Investment Objectives of the Underlying Funds") help achieve
     the Fund's investment objective.

     RESPONSE: The Registrant has amended its disclosure to clarify the Fund's
     use of the underlying funds listed in Appendix A. The disclosure now states
     that the "underlying Janus funds listed in Appendix A invest in varying
     percentages of equity securities, fixed income and alternative securities.
     These funds have been selected as potential investments because they
     represent a universe of investment strategies, asset categories and asset
     classes that may help achieve the Fund's investment objective."

8.   COMMENT: The Staff suggested that the Registrant amend its disclosure so
     that it is consistent with the Fund's investment objective of long term
     growth of capital with a secondary emphasis on income.

     RESPONSE: The Registrant acknowledges the comment and has updated the
     disclosure accordingly.

9.   COMMENT: The Staff questioned whether or not the "committee comprised of
     Janus Capital investment professionals" as referenced in the Fund's
     prospectuses is considered a managing team as defined under Item 5(a)(2) of
     Form N-1A.

     RESPONSE: The Registrant does not believe that the participation of the
     committee rises to the definition of a "managing team." Rather, as
     discussed during the call, the disclosure states the Fund's portfolio
     manager is responsible for the day-to-day management of the Fund and
     oversees trades on behalf of the Fund. The committee role is to normally
     review the process and related Fund allocations on a quarterly basis.



10.  COMMENT: With respect to the statement "When market conditions dictate a
     more defensive strategy, the Fund or an underlying fund may temporarily
     hold cash..." the Staff stated that this is inconsistent with Item 4 of
     Form N-1A.

     RESPONSE: The Registrant believes the disclosure describing a fund's
     ability to temporarily increase its cash position, under unusual
     circumstances, to protect assets or maintain liquidity in certain
     circumstances (e.g., to meet unusually large redemptions) is appropriate
     and no modifications are necessary at this time.

11.  COMMENT: With respect to the definition of the MPC Allocation Composite
     Index, as a "hypothetical" combination of unmanaged indices, the Staff
     asked for clarity as to the meaning of "hypothetical."

     RESPONSE: As discussed during the call, the index is an additional
     benchmark index for the Fund. The index is internally calculated and
     combines the total returns from three broad-based securities market indices
     resulting in a benchmark combination that, in Janus' opinion, more closely
     correlates with the Fund's three investment categories.

12.  COMMENT: The Staff suggests that the footnotes to the Fees and Expenses
     table follow the expense examples.

     RESPONSE: The Registrant believes that the most effective presentation of
     the information is reflected in the current disclosure and is consistent
     with Item 3 of Form N-1A. Additionally, General Instruction C.1(a) to Form
     N-1A provides that a fund should use document design techniques that
     promote effective communication which the Registrant believes is consistent
     with its current disclosure.

13.  COMMENT: The Staff indicated that it may request, in future reviews,
     additional disclosure regarding expense recoupment by Janus Capital
     permitted pursuant to an expense limitation agreement between the
     Registrant and Janus Capital.

     RESPONSE: The Registrant confirms that the Fund has the ability to recoup
     certain expenses as described in the Fund's expense limitation agreement.
     As previously discussed, the contractual expense waivers apply if total
     operating expenses (excluding certain expenses) exceed a certain limit, and
     recoupment is only possible if the expense ratio falls below the expense
     limit, and only for a period of three years subsequent to the Fund's
     commencement of operations.

14.  COMMENT: The Staff indicated that there appears to be a conflict between
     disclosure indicating the Fund's intent to operate under the classification
     of "diversified" and a statement indicating that the Fund's investment in
     any underlying fund may exceed 25% of the Fund's total assets, which, in
     the Staff's opinion, appears to be a diversification and/or concentration
     problem.

     RESPONSE: Section 5(b)(1) of the 1940 Act defines a "diversified company"
     as a management company that meets the following requirements:

     At least 75 per centum of the value of its total assets is represented by
     cash and cash items (including receivables), Government securities,
     securities of other investment companies, and other securities for the
     purposes of this calculation limited in respect of any one issuer to an
     amount not greater in value than 5 per centum of the value of the total
     assets of such management company and to not more than 10 per centum of the
     outstanding voting securities of such issuer.



     As a fund of funds, the MPC Fund meets the definition of a diversified
     company because at least 75% of its total assets are represented by other
     mutual funds. Section 5(b)(1) does not, by its terms, limit a Fund's
     investments in the securities of other investment companies.

     While the Fund does not have a 1940 Act concentration policy, its
     investment among underlying funds may result in 'indirect' concentration.
     Such disclosure is intended as a risk factor and not specific industry
     concentration. The indirect concentration risk has been disclosed in the
     prospectus.

15.  COMMENT: With respect to underlying fund risk disclosure pertaining to the
     nondiversification classification of such underlying funds, the Staff
     stated its view that Rule 13a-1 under the 1940 Act, is intended to apply to
     nondiversified funds which temporarily become diversified, not
     nondiversified funds which normally operate as diversified funds. It was
     the Staff's opinion that the disclosure should accurately reflect a fund's
     subclassification consistent with this view.

     RESPONSE: The Registrant confirms that the disclosure states when an
     underlying fund is classified as nondiversified. Item 2 of Form N-1A
     indicates that a fund classified as nondiversified include disclosure that
     it "may" invest a larger portion of its assets in fewer issuers. The
     Registrant believes its disclosure is consistent with Form N-1A.

Statement of Additional Information

16.  COMMENT: The Staff commented that a statement on the SAI cover seems to be
     incorporating by reference supplements that may be filed in the future and
     indicated that the statement may not be appropriate.

     RESPONSE: The Registrant believes that the statement complies with Rule
     8b-23 of the 1940 Act, and Rules 411 and 412 of the 1933 Act, which allow
     documents that are incorporated by reference into a registration statement
     to be subsequently modified or superseded by statements modifying or
     replacing existing statements contained in the registration statement. In
     addition, documents may be incorporated by reference as long as they have
     been filed with the Commission.

17.  COMMENT: With respect to the Fund's investment restriction related to
     securities eligible for resale pursuant to Rule 144A under the 1933 Act,
     the Staff questioned whether there was appropriate disclosure contained
     elsewhere in the SAI regarding liquidity issues associated with Rule 144A
     securities.

     RESPONSE: The Registrant acknowledges the comment and has modified its risk
     disclosure to indicate that Rule 144A securities may become illiquid if
     there is not a demand for the securities.

18.  COMMENT: The Staff requested clarification regarding the basis of the
     following statement: "The underlying funds may not acquire the securities
     of other investment companies or registered unit investment trusts in
     excess of the limits of Section 12(d)(1) of the 1940 Act in reliance on
     subparagraph (F) or subparagraph (G) of Section 12(d)(1)."

     RESPONSE: The Registrant notes that Section 12(d)(1)(G)(i)(IV) of the 1940
     Act states that an underlying fund of a fund that relies on Section
     12(d)(1)(G) must have a policy that prohibits it from also acquiring other
     funds in reliance on Section 12(d)(1)(F). As a result, the underlying fund
     must comply with the requirements of Section 12(d)(1)(A).



19.  COMMENT: With respect to the statement "Structured investments include a
     wide variety of instruments such as inverse floaters and collateralized
     debt obligations," the Staff stated that the use of these types of
     instruments may subject the Fund to risks associated with subprime
     mortgages and the associated market turmoil, and questioned whether or not
     there was appropriate risk disclosure surrounding these types of
     investments.

     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure has been included.

20.  COMMENT: With respect to disclosure related to "Remarketed Preferred
     Stock," the Staff suggested that the Registrant review its disclosure to
     ensure that appropriate risks are disclosed.

     RESPONSE: The Registrant acknowledges the comment and believes that
     appropriate risk disclosure has been included.

21.  COMMENT: The Staff requested that the Registrant provide a Tandy
     representation in a response letter to be filed as correspondence separate
     from the filing.

     RESPONSE: The Registrant provides its response below.

The Registrant acknowledges responsibility for the adequacy and accuracy of the
disclosure in the filings. In addition, the Registrant acknowledges that Staff
comments, or changes to disclosure in response to Staff comments in the filings
reviewed by the Staff, do not foreclose the Commission from taking any action
with respect to the filing.

If you have any concerns regarding the above responses, please call me at (303)
336-4562. Thank you for your assistance in this matter.

Regards,


/s/ Rodney A. DeWalt

Rodney A. DeWalt
Legal Counsel

cc:  Stephanie Grauerholz-Lofton, Esq.
     Cindy Antonson
     Donna Brungardt