GridView1.DataSource=MyDataTable

<asp:TemplateField HeaderText="[-]">
   <ItemTemplate>
      <asp:CheckBox runat="server"/>
   </ItemTemplate>
</asp:TemplateField>

Protected Sub Button1_Click(ByVal sender As Object, ByVal e As _
  System.EventArgs) Handles Button1.Click
   For Each MyRowX As GridViewRow In GridView1.Rows
      '... ich hab keine Ahnung
   Next
End Sub

Dim MyRowX As GridViewRow
Dim MyChkBox As New CheckBox
 
For Each MyRowX In GridView1.Rows
   Select Case DirectCast(MyRowX.FindControl("TestChkBox"), CheckBox).Checked
      Case False
         MsgBox(MyRowX.Cells(1).Text & " NEIN: unchecked")
      Case True
         MsgBox(MyRowX.Cells(1).Text & " JA: checked")
   End Select
Next