In almost all the web projects, we require a multiline TextBox control. It was annoying to find that maxLength property doesn't work on multiline textboxes. There is a workaround to accomplish this using RegularExpressionValidator. Following is the markup that will restrict the text box to maximum of 500 characters. OR You it can be done so easily using javascript functions. I suggest that we should put a javascript validator function so that user will not be able to enter characters more than the length specified, even cant paste any text with more than specified characters. Here are those javascript functions. TextBox Control Javascript: // Keep user from entering more than maxLe...