' SOIT:
With Sheets("Feuil1")
For i = 5 To 30
If IsDate(.Cells(1, i)) Then ComboBox1.AddItem Format(.Cells(1, i), "dd/mm/yyyy")
Next i
End With
'OU:
Dim Dat As Date
With Sheets("Feuil1")
For i = 5 To 30
If IsDate(.Cells(1, i)) Then
Dat = .Cells(1, i): ComboBox1.AddItem Dat
Next i
End With