Aneurysms of the middle cerebral bifurcation represent an interesting entity among intracranial saccular aneurysms. Their shape, size, situation, and in particular their relation to the middle cerebral trunk and its branches show wide variations. Topographical analysis of the angiograms offers a great deal of interest in planning surgery. Our experience with 289 patients with middle cerebral artery aneurysms operated on since 1977 are presented. Factors such as number of previous haemorrhages, timing of surgery, preoperative condition, major intraoperative bleeding or brain oedema and delayed postoperative deterioration play a major role in the outcome. Others such as severity of the subarachnoid bleed, age, size of the sac seem to have much less influence.