We used cranial computed tomography (CT) to evaluate 51 leukemic patients with or without central nervous system (CNS) symptoms. Among 17 symptomatic patients, nine had gross abnormalities on CT scans; leukemic infiltrations, infections (CNS aspergillosis), hemorrhages, and therapy-related complications were all evident. One with a leukemic infiltration showed a periventricular low density on the CT scans. The differential diagnosis of CT findings and the correlation between clinical and CT findings is described. The significance of a low-density area observed in an asymptomatic patient on long-term intrathecal methotrexate therapy for CNS leukemia is also discussed.