The easiest way to do this, is to buy the developer kit from activestate. This will allow you to make an activex componet with perl. After you have done that, you can now make calls to the componet from excel. Another option is to write an activex componet in c/vb and have it wrap around your perl program. Finaly, you can call your perl program from excel, then have your perl program use OLE to modify your excel spreadsheet.