<script runat="server">
   
    Dim rbl As RadioButtonList
    
    Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
                     
        If (Me.Session("rbl") IsNot Nothing) Then
            rbl = CType(Me.Session("rbl"), RadioButtonList)
        Else
            rbl = New RadioButtonList
            rbl.Items.Add(New System.Web.UI.WebControls.ListItem("test", "test", True))
            rbl.Items.Add(New System.Web.UI.WebControls.ListItem("test1", "test1", True))
            rbl.Items.Add(New System.Web.UI.WebControls.ListItem("test2", "test2", True))
            rbl.ID = "rbl"
            rbl.SelectedIndex =  1 
        End If
       
        PlaceHolder1.Controls.Add(rbl)
              
    End Sub
             
    Protected Sub Button3_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        Response.Write(rbl.SelectedItem.Text)
    End Sub

    Protected Sub Page_PreRender(ByVal sender As Object, ByVal e As System.EventArgs)
        Me.Session.Add("rbl", rbl)
    End Sub
</script>