You could look at something like this

http://www.exceltip.com/st/Compare_t...ce l/477.html

which is how to compare 2 worksheets but if you could be more specific in
you question then a more specific answer is likely.

Mike


"ClaireView" wrote:

My co-worker wanted to avoid entering duplicates in her Excel 2002 document.
I was very proud of myself for discovering Data Validation, and that worked
fine. Now the problem is harder:

She has one workbook and every day she adds a new worksheet to it. She
wants to make sure the data she's entering wasn't also entered on a previous
day. This is beyond me. Any ideas?