Certification Pursuant to Section 1350 of Chapter 63 of Title 18
                            of the United States Code


I, Ralph C.  Eucher,  President of Principal  LargeCap  Stock Index Fund,  Inc.,
certify  that (i) the Form  N-CSR for the  period  ended  April 30,  2003  fully
complies  with the  requirements  of  Section  13(a) or 15(d) of the  Securities
Exchange  Act of 1934 and (ii) the  information  contained in the Form N-CSR for
the period ended April 30, 2003 fairly presents,  in all material respects,  the
financial  condition and results of operations of Principal LargeCap Stock Index
Fund, Inc.


Date: June 19, 2003                     /s/ Ralph C. Eucher
                                    -------------------------------
                                    Ralph C. Eucher
                                    President


        Certification Pursuant to Section 1350 of Chapter 63 of Title 18
                            of the United States Code




I, Jill R.  Brown,  Vice  President  and Chief  Financial  Officer of  Principal
LargeCap Stock Index Fund, Inc.,  certify that (i) the Form N-CSR for the period
ended April 30, 2003 fully  complies with the  requirements  of Section 13(a) or
15(d) of the Securities Exchange Act of 1934 and (ii) the information  contained
in the Form N-CSR for the period  ended April 30, 2003 fairly  presents,  in all
material  respects,  the  financial  condition  and  results  of  operations  of
Principal LargeCap Stock Index Fund, Inc.


Date: June 19, 2003                     /s/ Jill R. Brown
                                    -------------------------------
                                    Jill R. Brown
                                    Vice President and Chief Financial Officer