I assume you mean they display on the menu while you are using the site, but not after you leave the site. I'm not aware of any built-in way to block sites from adding items to Firefox's right-click context menu. There might be an add-on to do it. ---- If the problem is that you get a completely different context menu, there is a setting in Firefox you can change that should allow you to always have access Firefox's normal right-click context menu. (1) In a new tab, type or paste '''about:config''' in the address bar and press Enter/Return. Click the button promising to be careful. (2) In the search box above the list, type or paste '''contex''' and pause while the list is filtered (3) Double-click the '''dom.event.contextmenu.enabled''' preference to switch it from true to false Notes: (1) With this change, when you want to access a site's custom context menu, you can "peel off" Firefox's menu from in front of it by pressing and releasing the Alt key. (2) If the site displays a prompt, you may need to interact with the prompt first before Firefox's menu displays (e.g., [http://www.jeffersonscher.com/]) (3) Obviously sites are aware of this and may have found ways to hack around it. If there are particular problem pages, do you want to provide a link? There's also this add-on I haven't tried: https://addons.mozilla.org/firefox/addon/righttoclick/