I tried several ways to fulfill the action: Protected Sub btnSave_Click(sender As Object, e As EventArgs) Handles btnSave.Click saveLestijden() 'Response.Write(" { window.close(); }") 'Page.ClientScript.RegisterStartupScript(Page.GetType(), "alert", "window.close();", True) 'Page.ClientScript.RegisterOnSubmitStatement(Page.GetType(), "closePage", "window.onunload = window.close();") Page.ClientScript.RegisterOnSubmitStatement(Page.GetType(), "closePage", "window.onunload = window.opener.close();") End Sub

No one is working If this is not possible, is there a way to close the window by for example a button ( also after a postback) I tried : Protected Sub btnTerug_Click(sender As Object, e As EventArgs) Handles btnTerug.Click

    Dim Script As String = "window.close();"
    System.Web.UI.ScriptManager.RegisterClientScriptBlock(btnTerug, Me.GetType(), "Test", Script, True)
End Sub

also nothing works. Before the postback I can close the window, but after savelestijden() the button does not work. PLease help ....