SUMPRODUCT comes to mind ..
Try something like this:
=SUMPRODUCT(--(A2:A100="XX"),C2:C100)
assuming the lookup value is "XX" within A2:A100
and the corresponding values to be summed are within C2:C100

Signature
Max
Singapore
http://savefile.com/projects/236895
xdemechanik
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> I want to use the vlookup formula in a worksheet that contains several
> results for the reference that the function Vlookup is looking for.How can i
> make the function Vlookup search for all the results ( not only the first
> rox) and make the sum of them?