Dim TrouverX As Boolean
TrouverX = False
Dim PremierX As Integer, DernierX As Integer
Dim I As Integer
For I = 2 To Range("A65536").End(xlUp).Row
If Cells(I, 1) = "X" And TrouverX = False Then
PremierX = I
TrouverX = True
End If
If Cells(I, 1) = "X" And TrouverX = True Then
DernierX = I
End If
Next I
MsgBox ("1° X : " & PremierX & " - dernier x : " & DernierX)