One way.

You can use a formula like this in, say, B4:

=IF(OR(COUNTA(A1:A4)=4,COUNTBLANK(A1:A4)=4),"","Al l 4 cells must be either
filled or left empty")

Maybe give it a bold red font.

--
Biff
Microsoft Excel MVP


"Mary Lancaster" wrote in message
...
Hi,
I hope someone can help me with this. I have four cells A1:A4. If all four
cells contain data or are blank then thats okay. But if 1, 2 or 3 cells
contain data then I want a warning that all cells must be blank or contain
data.

Thanks
Mary