What lookup function are you using? If you use VLOOKUP you can use FALSE or
0 to find an exact match

=VLOOKUP(A1,B2:C400,2,0)

will return #N/A if lookup is not found

--

Regards,

Peo Sjoblom

"Feldy" wrote in message
...
When using the lookup function in Excel 2003, it would be extremely
helpful
to have an error appear if the looked up item does not appear in the list.
Example: If I have a small list of students in list A and I'm trying to
look
up the corresponding teacher in list B, it returns a teacher for every
student in list A, even if that student is not in list B, and therefore,
it
is the wrong information. I would rather have it display an error
message,
so that I know that something is missing.