A retrospective review of 126 patients with multiple aneurysms seen over a 10 year period was undertaken. They had a total of 302 aneurysms. Thirty-seven percent of the patients were males, and 63% were females. Direct operations were performed on 97 cases. Both the ruptured and unruptured aneurysms were treated in 71% (69 of the 97 cases), and only the ruptured aneurysms were treated in 29% (28). In 69 cases in whom both ruptured and unruptured aneurysms were treated, one-stage operations were used for 48 cases, and two-stage operations were used for 21 cases. Thirty-four of the 48 cases, who were treated in one-stage operations, were operated on by day 4 after subarachnoid haemorrhage. In 12 cases, a total of 13 small unruptured aneurysms, which had not been found by preoperative angiograms, were discovered during surgery, and 9 of the 13 were discovered while removing blood clots to reduce cerebral vasospasm. Regardless of the operative method selected and the timing of operations, the surgical outcome of patients with multiple aneurysms was comparable to that of the 228 cases with single aneurysms treated during the same period at the same hospital. The analysis of this study suggest that surgical results for multiple aneurysms are satisfactory, even for early operations. Further, the actual incidence of multiple aneurysms may be higher than has been reported to date because small unruptured aneurysms which have been discovered during clot removal may not have been reported.