Sub test()
Dim I As Long
Dim CC As Range
I = 1
While Range("B" & I) <> ""
Set CC = Range("A1:A500").Find(Range("B" & I).Value, LookIn:=xlValues)
If CC Is Nothing Then
'la je lance la macro du while ....
MsgBox "Absent " & Range("B" & I)
End If
I = I + 1
Wend
End Sub