Hi Simora,
Change ActiveCell to MyCell:
Sub exa()
Dim MyCell As Range, MyRange As Range
Set MyRange = Range("M204:U204")
For Each MyCell In MyRange
If MyCell.Value < 1 Or MyCell.Value = "" Then
MyCell.EntireColumn.Hidden = True
End If
Next MyCell
End Sub
ActiveCell is not changing, as the ActiveCell is just whatever cell is selected on the ActiveSheet.
BTW, you might want to be careful in titling your thread. Deleting columns is of course a bit different than hiding them for a bit.
Hope that helps,
Mark