It is a standard feature of Excel. In HELP, type "Validation".

--
Kind regards,

Niek Otten
Microsoft MVP - Excel

"S1L1Y1" wrote in message
...
Thank You. where can I get the validation tool or how?
"Niek Otten" wrote in message
...
http://www.cpearson.com/excel/NoDupEntry.aspx

and

http://www.cpearson.com/excel/deleti...eDuplicateRows

--
Kind regards,

Niek Otten
Microsoft MVP - Excel

"S1L1Y1" wrote in message
...
I have Office XP. I am working with Excel How can I check if I didn't
enter
something twice? I found that I entered many rows twice. It would take
me
at
least an hour to go through the whole file.
Sol