Try this code, ofcourse this is meant for a combobox but I am sure someone can do this for listbox. I would have done it but don't have VB installed on the computer I am serfing the net from

VB Code:
  1. Private Const CB_FINDSTRINGEXACT = &H158
  2. Private Const CB_ERR = (-1)
  3.  
  4. Private Declare Function SendMessage Lib "user32" Alias "SendMessageA" _
  5.             (ByVal hwnd As Long, ByVal wMsg As Long, _
  6.             ByVal wParam As Long, lParam As Long) As Long
  7.  
  8. Private Sub cmdRemoveDups()
  9.     Dim x As Integer, y As Integer
  10.  
  11.     For x = cmbSortServiceDate.ListCount - 1 To 0 Step (-1)
  12.         y = SendMessage(cmbSortServiceDate.hwnd, CB_FINDSTRINGEXACT, CB_ERR, ByVal cmbSortServiceDate.List(x))
  13.        
  14.         If y <> x And y <> CB_ERR Then
  15.             cmbSortServiceDate.RemoveItem x
  16.         End If
  17.     Next
  18. End Sub