A group of 33 patients with 34 aneurysms of the pericallosal artery and its branches are reported. They were treated in the Department of Neurosurgery, Medical Academy in Warsaw in the years 1965-1981. In 4 patients coexistence of other cerebral vascular anomalies (aneurysms of other location and/or angiomas) was demonstrated. The group comprised 21 men and 12 women aged from 7 to 60 years. Nine patients were not operated on, 8 of them died due to haemorrhagic brain damage and one gave no consent to operation. Out of surgically treated 24 patients in 3 cases the common carotid artery was ligated in 4 cases the wall of the aneurysm was reinforced with plastic mass, and in 17 cases the neck of the aneurysm was closed with a clip. In the clinical group I (Botterell's scale) 7 patients were treated surgically, in group II - 5, in group III - 9 and in group IV - 3. The immediate operative mortality was 8.5% (2 patients). One patient died 2 months after the operation from other disease. Deterioration of the neurological status occurred in 33% of cases (8 patients). Late result of the treatment was known in 16 cases with a mean follow-up of 4 years. Six patients returned to work, five resumed work with restrictions, and five other could not work and required care. The results of surgical treatment depended, in the first place, on the clinical state of the patient and the surgical risk was not greater than in cases of aneurysms of other location.