in an adjacent column

=Countif([Book2.xls]Sheet1!A:A,A1)

drag down the column

repeat in Book2 checking Book1.

then you can filter on the results.

See Chip Pearson's site for working with duplicates and uniques:

http://www.cpearson.com/excel/duplicat.htm

--
Regards,
Tom Ogilvy

"Joshua" wrote in message
...
I have a list of users on 2 workbooks. I need to compare the 2 workbooks
and
see who is one list and not the other. Because of the size of these lists
I
could not do it manually. Is there an automated way I could use to do
this
and reproduce it on a monthly basis