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Principal Financial Group                    Principal Life Insurance Company
Des Moines, Iowa USA 50392-0001
(515) 247-5111

January 25, 1999

Board of Directors
Principal Cash Management Fund, Inc.
Des Moines, IA 50392-0200

Re:      Registration Statement on Form N-14
         Pursuant to Securities Act of 1933


I am familiar with the proposed issuance by Principal Cash Management Fund,
Inc.  of shares of its  Class A common  stock,  par  value  $.01 per  share,  in
connection  with the transfer to it of the assets and  liabilities  of Principal
Tax-Exempt Cash Management Fund, Inc.  pursuant to the terms of an Agreement and
Plan of Acquisition to which they are parties (the "Shares"). I am also familiar
with the above-referenced  Registration Statement (the "Registration Statement")
filed with the Securities and Exchange Commission relating to the offer and sale
of Shares. Based upon such investigation as I have deemed necessary, I am of the
opinion that the Shares,  when issued in accordance  with the terms described in
the   Registration   Statement,   will  be  legally   issued,   fully  paid  and
non-assessable.

I hereby consent to the filing of this opinion as a exhibit to the  Registration
Statement.

Very truly yours,


/s/ Michael D. Roughton     
Michael D. Roughton
Counsel