Preliminary studies with sonography indicated that a reduced brain mantle index and dilated ventricles were frequently seen in patients with chronic Schistosoma mansoni infection. Computerized tomography (CT) was used to confirm our earlier observations and to obtain more accurate measures. Brain scans of 25 patients with chronic S. mansoni infection showed mild to moderate degrees of cortical atrophy in 9 cases (36%) and central atrophy in 3 (12%). The remaining 16 subjects and 10 controls showed normal brain scans. The present study is the first report documented by CT showing a significant correlation between chronic S. mansoni infection and cerebral atrophy.