Private Sub TextBox1_KeyPress(ByVal sender As Object, _
  ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
 
  If e.KeyChar = Microsoft.VisualBasic.ChrW(13) Then
    MsgBox("Enter wurde gedrückt!")
  End If
End Sub

Private Sub TextBox1_KeyPress(ByVal sender As Object, _
  ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
 
  Dim KeyAscii As Long
 
  KeyAscii = Asc(e.KeyChar)
  Select Case KeyAscii
    Case 48 To 57, 8, 32
      <font color=green>' Zahlen, Backspace und Space zulassen</font>
 
    Case Else
      <font color=green>' Zeichenausgabe unterdrücken</font>
      e.Handled = True
  End Select
End Sub