Two patients with giant complex saccular aneurysms of the proximal basilar artery were managed with flow-reversal using the endovascular route. Complete obliteration of the aneurysm was successful in one patient resulting in long term survival (8 year follow-up completed). Incomplete obliteration of the aneurysm persisted in the other patient, resulting in recurrence and a fatal haemorrhage one year after treatment. Endovascular flow-reversal is a good treatment option for these lesions with a high surgical risk. However, persistent incomplete thrombosis of these aneurysms following flow-reversal should lead to the consideration of alternate treatment strategies.