The authors analyzed the radiographs(brain CT and cerebral angiograms) and medical & surgical records of 54 cases of ruptured anterior communicating artery aneurysms resulted in operations at our hospital from January 1991 to December 1995. The results were summarized as follows: 1) The rate of incidence was found to be highest in sixth decade and the ratio of male to female was 1:1. 2) On the preoperative brain CT, ventricular or cerebral hemorrhage combined cases had high Hunt-Hess and Fisher grades. 3) Of 54 cases, hypertension was observed in 20 cases(37%). Hypertension had no effect on the admission Hunt-Hess and Fisher grades. 4) Classification of the anterior communicating artery aneurysms according to its directions were as follows; anterior direction in 57.4%, superior direction in 18.5%, posterior direction in 13%, inferior direction in 11.1%. 5) The afferent artery of anterior communicating artery aneurysms were as follows; left A1 in 38 cases(70.4%), right A1 in 12 cases(22,2%), bilateral A1 in 4 cases(7.4%). 6) The ranges of diameters of the aneurysm was as follows;6-10mm in 57.4%, below 5mm in 22.2%. 7) The posteriorly directing aneurysms showed less favorable preoperative state, and preoperative hydrocephalus was most common on the posteriorly directing aneurysms. 8) There was no significant relationship between direction of aneurysm and prognosis. However, better Hunt-Hess grades seem to correlate better prognosis. 9) The operation was performed by pterional approach in all cases, the approach side was selected for the presence of dominant feeding artery in 50 cases(92.6%). 10) Overall mortality rate was 1.8%, the patients who died are of the older age group and the cause of death was medical complication in 6 cases.