 <p>Here is a good SO question that i think addresses this:</p> <p><a href="http://stackoverflow.com/questions/2611350/intercept-paste-event-on-htmleditor-winforms">Intercept paste event on HtmlEditor WinForms</a></p> <p>You have to sub-class it and stop the paste message from getting farther down, by overriding WndPrc. Then, call your own function to handle the paste. </p> <p>I think there is an easier way to locate the paste message, though. Ignore his code for inserting the content, since that doesn't apply to an RTF.</p>