Steve,

The most simple solution is to include the null condition in the formula:

Sub Steve()
Intersect(Range("E:E"), ActiveSheet.UsedRange).FormulaR1C1 = _
"=IF(RC[-4]="""",RC[-2]+RC[-1],"""")"
End Sub

HTH,
Bernie
MS Excel MVP

"Steve" wrote in message
...
Hi

I would like to populate column E with a formula (column C
+ column D) where the the value of Column A is null.

Is this possible ?

Thank you in advance
Steve