Debra,
Thanks this works fine. Is there a way to have an Error Alert generated when
counta =1 (when the one of the cells has data selected from the list)?

Thanks,
Keith



"Debra Dalgleish" <dsd@contexturesXSPAM.com> wrote in message
news:42725588.3000400@contexturesXSPAM.com...
> Create a named range with your list of options, e.g. MyList. There are
> instructions here:
>
> http://www.contextures.com/xlNames01.html
>
> Choose Insert>Name>Define
> Type the name: NoList
> In the Refers to box, type:
>
> =OFFSET(Sheet1!$G$1,0,0,0,1)
> You can change the Sheet1!$G$1 reference to a sheet and cell
> in your workbook
>
> Click OK
>
> Select cells A1:B1
> Choose Data>Validation
> From the Allow dropdown, select List
> In the Source box, type:
>
> =IF(COUNTA($A$1:$B$1)=0,MyList,NoList)
>
> Click OK
>
> Keith wrote:
>> Two cells, using data validation | custom... COUNTA($A1:$B1)<2
>> This works fine to prevent data in both cells.
>> But I also want to use a drop down list for the data selection in A1 and
>> B1,
>> How can I do both?
>> Thanks,
>> Keith
>>
>>
>>
>
>
> --
> Debra Dalgleish
> Excel FAQ, Tips & Book List
> http://www.contextures.com/tiptech.html
>