Sub colorEmptyRows()
Dim LastRow As Long
Dim r As Long
LastRow = ActiveSheet.UsedRange.Row - 1 + ActiveSheet.UsedRange.Rows.Count
Application.ScreenUpdating = False
For r = LastRow To 1 Step -1
If Application.WorksheetFunction.CountA(Rows(r)) = 0 _
Then
Rows(r).Interior.ColorIndex = 3
Next r
End Sub