Public Class AutoCompleteComboBox
    Inherits System.Windows.Forms.ComboBox
 
    Dim sw As Boolean
 
    Sub New()
      Me.Sorted = True
    End Sub
 
    Protected Overrides Sub ontextchanged(ByVal e As EventArgs)
      MyBase.OnTextChanged(e)
      With Me
        If Len(.Text) > 0 Then
          If sw And Len(.Text) > 0 Then sw = False : Exit Sub
          sw = True
          Dim i As Integer = Me.FindString(Me.Text)
          If i >= 0 Then
            Dim k As Integer = Len(.Text)
            Me.SelectedIndex = i
            .SelectionStart = k
            .SelectionLength = Len(.Text) - k
          End If
        End If
      End With
      sw = False
    End Sub
 
    Protected Overrides Sub OnKeyDown(ByVal e As _
      System.Windows.Forms.KeyEventArgs)
      If e.KeyCode = Keys.Delete Then sw = True
      If e.KeyCode = Keys.Back And Me.SelectionStart > 0 Then
        Me.Text = Me.Text.Substring(0, Me.SelectionStart - 1)
      End If
      If e.KeyCode = Keys.Enter Then
        Dim i As Integer = Me.FindString(Me.Text)
        If i < 0 Then Me.Items.Add(Me.Text)
      End If
    End Sub
 
  End Class

Private Sub Form1_Load(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles MyBase.Load
    Dim ctl As New AutoCompleteComboBox
    With ctl
      .Top = 100
      .Left = 50
      .Width = 200
      .DropDownWidth = 200
      Me.Controls.Add(ctl)
      For i As Integer = 1 To 100
        Dim str As String = ""
        For k As Integer = 1 To CInt(5 + 20 * Rnd())
          str &= Chr(CInt(97 + 25 * Rnd()))
        Next
        .Items.Add(str)
      Next
    End With
  End Sub

VB@rchiv its the Best