[Janus letterhead]



April 21, 2009


EDGAR Operations Branch
Securities and Exchange Commission
Division of Investment Management
100 F Street, N.E.
Washington, DC 20549-0505

Re:  JANUS INVESTMENT FUND (the "Registrant")
     1933 Act File No. 2-34393
     1940 Act File No. 811-1879

Dear Sir or Madam:

The Registrant is transmitting today for filing under the Securities Act of
1933, as amended, Pre-Effective Amendment No. 1 to the registration statement on
Form N-14 (the "Registration Statement") relating to the registration of shares
of beneficial interest to be issued in connection with the reorganization of
Janus Adviser Perkins Mid Cap Value Fund (the "Acquired Fund"), a series of
Janus Adviser Series, into Perkins Mid Cap Value Fund (the "Acquiring Fund"), a
series of the Registrant (the "Reorganization). The purpose for filing the
Registration Statement is to revise the pro forma financial statements that were
filed as a part of the initial registration statement filed on Form N-14 on
March 17, 2009. (Any additional comments received from the Staff will be
addressed under a separate filing.) The pro forma financial statements were
revised as a result of amendments to the methodology used in calculating the
starting NAV for the Acquiring Fund's new shares classes, which were discussed
with the Staff on an April 16, 2009 telephone conference call. The statement of
additional information has been redlined to show changes from the initial
registration statement. Since the Staff has previously reviewed the contents of
the Registration Statement, the Registrant respectfully requests selective
review of only the above referenced revisions.

The Registration Statement is also being filed under the Securities Exchange Act
of 1934, as amended. No filing fee is due in connection with this filing.

If you have any questions regarding this filing, please call me at (303)
336-4562.

Sincerely,

/s/ Rodney A. DeWalt

Rodney A. DeWalt
Legal Counsel

Enclosures

cc:  Stephanie Grauerholz-Lofton, Esq.
     Larry Greene, Esq.
     Robin R. Nesbitt, Esq.
     Cindy A. Antonson
     Donna Brungardt