This question has been posted and answered many times since the release of Firefox 4. There is no longer a user-settable time limit setting in Firefox 4 and newer versions for History. You can not set how long to retain History after Firefox 3.6.x. Firefox determines automatically how many pages can be kept without affecting the performance of Firefox based on your system's resources. You can see the current value via the read-only pref places.history.expiration.transient_max_pages on the about:config page. If you try to reset the value, it will automatically reset to the best calculated value so as to not degrade Firefox's performance. See --> http://kb.mozillazine.org/About:config You can reset the no longer used browser.history_expire_days* preferences from older Firefox versions to remove them on the next start. See --> http://blog.bonardo.net/2010/01/20/places-got-async-expiration See --> https://bugzilla.mozilla.org/show_bug.cgi?id=701152 (do not post in bug reports; for use of developers discussions only) You can try the following extension to export your history to a file on a regular basis before it is automatically deleted, but you may end up with duplicates https://addons.mozilla.org/en-US/firefox/addon/history-export/?src=ss If this reply solves your problem, please click "Solved It" next to this reply when signed-in to the forum.