The ReadOnly TextBox will ignore the submitted text , this change due to security reasons . For example you want to use the textbox and you don't want to let the user to change the textbox manually , now the problem is that the selected value will not be accepted by the textbox when the user submit the form , because the textbox is in readonly mode , in this case you need to manually set the submitted textbox value , you can easily use the values that is submitted via form collection , something like this: Protected void Page_Load( object Sender, EventArgs e) { TextBox1.Text = Server.HtmlEncode(Request.Form(TextBox1.UniqueID)) }