Private Function ReadColumnOfXlsFile(ByVal XlsFile As String, ByVal Col As _
     String) As List(Of String)
        Dim MyList As New List(Of String)
 
        Try
            Dim fXlsFile As FileInfo
 
            If XlsFile.Trim.Length > 0 Then
                fXlsFile = New FileInfo(XlsFile)
                If Not fXlsFile.Exists Then Throw New Exception("File does not" & _
                  "exist.")
            Else
                Throw New Exception("Path empty.")
            End If
 
            Dim _XlsApp As New Excel.Application
            Dim _Workbook As Excel.Workbook = _XlsApp.Workbooks.Open( _
              fXlsFile.FullName)
            Dim _Sheet As Excel.Worksheet = _Workbook.Sheets(1) ' First Sheet
 
            _XlsApp.Visible = False
            _Sheet.Activate()
 
            Dim sTemp As String = String.Empty
            For RowIndex As Integer = 1 To _Sheet.UsedRange.Rows.Count
                Application.DoEvents()
                sTemp = _Sheet.Range(Col & RowIndex).Text.ToString
                ' MyList.Add(sTemp)
                If sTemp.Trim.Length > 0 Then MyList.Add(sTemp.Trim) 'Do not 
                ' Add empty item
            Next
 
            _Workbook.Close()
            _XlsApp.Quit()
 
            System.Runtime.InteropServices.Marshal.ReleaseComObject(_Sheet)
            System.Runtime.InteropServices.Marshal.ReleaseComObject(_Workbook)
            System.Runtime.InteropServices.Marshal.ReleaseComObject(_XlsApp)
 
        Catch ex As Exception
            MsgBox(ex.Message)
            MyList = New List(Of String)
        End Try
 
        Return MyList
    End Function

    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As _
      System.EventArgs) Handles Button1.Click
        Dim dlg As New OpenFileDialog
        dlg.Filter = "Excel Dokument (*.xls)|*.xls"
 
        If dlg.ShowDialog = Windows.Forms.DialogResult.OK Then
            ListBox1.Items.Clear()
            ListBox1.Items.AddRange(Me.ReadColumnOfXlsFile(dlg.FileName, _
              "A").ToArray)
        End If
        MsgBox(ListBox1.Items.Count & " Werte gefunden.")
    End Sub