Thanks all, I have my problem solved. My CMS (TYPO3) was set to prefix local anchors (needed for the URL re-writing extension realurl) and this was changing the href's by adding a whole url.
Since I can't turn of this function without switching of realurl I just alter the anchors before calling tabs() with the following (for those who also experience this when using TYPO3 with realurl): // RealUrl uses local anchor prefixing. This must be removed from the tab links before calling tabs(); $tabLinks = $('#relatedTabBar li a'); $numOfTabs = $tabLinks.length; for (var index = 0; index < $numOfTabs; index ++) { $oldAnchor = $tabLinks.attr('href'); $hashPos = $oldAnchor.indexOf('#'); $newAnchor = $oldAnchor.substr($hashPos); $tabLinks.attr('href', $newAnchor); } // Related Tabs on single view $("#relatedTabs").tabs(); Thanks again for the help. Now I just have to replace the dummy tab content with the real content!