Try this:

=SUM(SUMIF(INDIRECT("Sheet"&{1,2,3}&"!A:A"),"EU",I NDIRECT("Sheet"&{1,2,3}&"!C:C")))


"andy" wrote:

i would like to sum all values in column C of different sheets when column A
of these sheets matches a certain value.

i tried the following:
sumif(Sheet1:Sheet3!$A:$A,"EU",Sheet1:Sheet3!C:C)
and
sumproduct(--(Sheet1:Sheet3!$A1:$A1000="EU"),Sheet1:Sheet3!C1:C 1000)

either way no result however.

thanks for helping.
andy