Bonsoir MarcDU
Voici, pas très compliqué
Private Sub Workbook_BeforeSave(ByVal SaveAsUI As Boolean, Cancel As Boolean)
With Sheets("MaFeuille")
If .Range("C3") = "" And .Range("C4") = "" Then
MsgBox "Merci de compléter les champs obligatoires en C3 et C4 SVP", vbCritical, "OUPS..."
Cancel = True
End If
End With
End Sub
A+