Thirty-nine cases of brain abscess diagnosed since the advent of the computed tomographic (CT) scan were analyzed for factors influencing the outcome. The mortality rate was 13%, and severe sequelae were present in 22% of the survivors. The mean delay between occurrence of the first symptoms and hospitalization was significantly shorter for the 12 patients with poor outcome (death or severe sequelae) than for the 25 who recovered (fully or with moderate sequelae). Moreover, severely impaired mental status and neurological impairment at admission were associated with a poor outcome in terms of both mortality and sequelae. In all cases with fatal outcome or severe sequelae, the diagnosis was made and treatment was initiated within 24 hours of admission. There was no apparent correlation between the outcome and the presence or type of predisposing factors, the radiological, biological, or microbiological findings, or the treatment modalities. Thus, with the advent of the CT scan and the possibility of early diagnosis and treatment, the prognosis of brain abscess appears to be mainly determined by the rapidity of progression of the disease before hospitalization and the patient's mental status on admission.