Sixty-six consecutive patients with brain abscesses referred to a department of neurosurgery during a 10-year period and treated with cefotaxime were studied retrospectively by means of a prospectively designed protocol whose main areas of emphasis were duration of antibiotic treatment, sterilization rate, clinical outcome in relation to prognostic factors, and side effects. Sixty-two of these patients were treated additionally with metronidazole, and surgery was performed in 53 patients. Mental status was altered in 33 patients, 11 of whom were comatose. Rupture of the abscess into the ventricles occurred in eight patients. Death was attributable to brain abscess formation in three patients (4.5%). Forty-six percent of the surviving patients recovered without any neurological deficits. Reversible adverse reactions, which occurred in 38 patients, were the most common reason for withdrawal of cefotaxime. In 76% of these cases, there was a significant improvement before the onset of the adverse reaction. The median duration of parenteral antibiotic treatment was 36, 41, 22, and 46 days in patients treated with excision, aspiration, evacuation of subdural empyema, and antibiotics alone, respectively. Taking prognostic factors into consideration, mortality attributable to brain abscess was lower than previously reported. This finding, along with the abscess sterilization results, indicates that cefotaxime in combination with metronidazole is a highly effective treatment but is associated with a high frequency of reversible side effects. The results indicate that a shorter duration of treatment should be investigated.