I'd use a formula in another cell. Then format it in nice big, bold, red
letters:

=if(and(a1="",b1<""),"Please put something in A1","")



Chris wrote:

Does anyone have any ideas how to make a cell compulsory if the cell next to
it has been filled in?
Can't see how to do it through validation. Don't want to use VBcode as you
can disable this when opening the file.

--

Dave Peterson