Seven patients with brain abscess underwent CT-guided stereotactic aspiration using Iseki's stereotactic apparatus. Three of them were under the age of fifteen and four were older than thirty. The lesions were single and round in four cases, multilobular in two and multiple in one patient. Operations were performed after systemic administration of antibiotics for more than two weeks and after capsule formation was confirmed on CTs. Preoperative volume of the abscesses was estimated from CTs. The target point chosen was the center of the ring of the largest diameter in the enhanced lesion. Abscess was aspirated under monitoring with intraoperative CT scan. No continuous drainage was performed and no antibiotics were given directly into the abscess cavity. In all cases the center of the abscess was punctured with a single trial. Average volume of the preoperative brain abscesses was 18.8ml. Aspirated volume at the time of the operation averaged 16.9ml and all the abscesses decreased to unmeasurable size on CTs. In five of seven patients abscesses were cured after a single aspiration, and in one case after the second operation. One case required extirpation of the lesion. During the follow-up period of four months to five and a half years six patients showed no recurrence. One patient died of unrelated cause four and a half years after the operation. No operative complication was noted. There was no operative morbidity or mortality. Using a CT guided stereotactic method, brain abscess is punctured so accurately, regardless of its location and size, that damage to the surrounding brain during operation can be minimized. Therefore it is highly possible to aspirate abscesses completely.(ABSTRACT TRUNCATED AT 250 WORDS)