Sorry I may have misread you post.

If you want to prevent duplicates when you add new data then:-

Select your range from A1 down then

Data|Validation|Formula is

and paste this in

=COUNTIF($A$1:$A$1000,A1)=1

This will prevent the addition of duplicates in that range.

Mike

"LO in Sweden" wrote:

Hello!

I have around 2000 articel nr. in a column (A) and add new sometimes.
Then I add new I wish to check so I dont get any duplicate.

Can I do that easy?

Thanks
LO in Sweden