Private Sub UserForm_Initialize()
Dim m As Object, t,i as long
Set m = CreateObject("Scripting.Dictionary")
t = Range("a2:a" & Cells(Rows.Count, 1).End(3).Row)
For i = LBound(t, 1) To UBound(t, 1): m(t(i, 1)) = "": Next i
ComboBox1.List = m.keys
End Sub