VB Code:
  1. Dim i1 As Integer, i2 As Integer

  2. For i1 = 0 To List1.ListCount - 1

  3.     For i2 = 0 To List2.ListCount - 1

  4.         List3.AddItem List1.List(i1) & List2.List(i2)

  5.     Next

  6. Next