Is Help > Check for Updates greyed-out in Firefox? <br /> If that option is available, have you clicked on it to have it check for an update from Mozilla? <br /> If it is greyed-out, you probably have a version of Firefox that came with your Linux distro. Those versions of Firefox aren't updated through Mozilla, but rather through your distro's program repository with the other programs that came with that distro or were installed from the repository. Use System Tools > Updates (or wherever in your Menus that your distro has system updates) to check for Updates.