Alternatively place the UDF below in a standard module.
Select the range of cells to test
Use Conditional Formatting with
Cell Formula is =MYFORMULA(A1)=TRUE
OF course, the cell reference must be to you first cell
best wishes

Function myformula(mycell)
mytest = mycell.Formula
mytest = Mid(mytest, 1, 11)
If mytest = "=SUMPRODUCT" Then
myformula = True
Else
myformula = False
End If
End Function

--
Bernard V Liengme
www.stfx.ca/people/bliengme
remove caps from email

"Dave F" wrote in message
...
I have a large spreadsheet, comprising a range of about 100000 individual
cells, a number of which cells are running various flavors of SUMPRODUCT
calculations. Is there a macro I can write which would scan all the
cells'
formulas and highlight those cells whose formulas contain SUMPRODUCT?

Dave
--
Brevity is the soul of wit.