Endovascular treatment of ruptured vertebrobasilar artery aneurysms with Gugliemi detachable coils (GDC) has become an alternative to surgery. Mid-term angiographic follow-up can now be reported. Of 111 vertebrobasilar aneurysms in 110 patients we treated with GDC since 1992, 53 underwent angiography within 1 year and 59 after more than 18 months. We did not achieve complete occlusion on initial treatment of 23 aneurysms (21%). Complications were observed in 19 patients (17%), leading to permanent clinical disability in eight. Enlargement of the neck or reopening was seen in 12 (23%) of 53 aneurysms followed by angiography within 12 months. Documented recanalisation was treated in four (8%). Angiography was performed after 18-78 months in 59 patients, of whom nine, including three with initially incomplete occlusions, were retreated with GDC. Within the entire second observation period, three (5%) of the 59 patients had a further haemorrhage and were retreated with GDC. Rebleeding proved to be the only factor influencing the clinical outcome of retreated patients.