We evaluated the behavior of 38 children with standard-risk and high-risk acute lymphoblastic leukemia who received corticosteroids as part of their antileukemia chemotherapy. Each patient was assessed on two occasions: 16 weeks following remission and 1 year thereafter. Parent reports on emotional lability, attention span/hyperactivity, sleep disturbance, listlessness, peer relations, and depressed mood were obtained for 4 consecutive weeks: week before, week during, and 2 weeks after treatment administration. At the 16 week evaluation, standard-risk (N = 17) and high-risk (N = 21) treatment differed by steroid dose and systemic chemotherapy, while at the 1 year testing, treatment differed only by steroid dose (prednisone 40 mg/m2 vs. 120 mg/m2). Statistically significant changes in all measures were observed during treatment as compared with before and after treatment for both risk groups and assessment times. High-risk patients exhibited greater behavioral effects than standard-risk patients only for emotional lability, listlessness, and depressed mood at the 16 week testing, when both steroid dose and chemotherapy differed. Girls had slightly greater behavioral effects than boys, while no influence of age was observed. At the doses tested, steroid dose per se does not appear to be the primary variable affecting behavioral changes.