Early and late effects of treatment for acute lymphoblastic leukemia (ALL) on weight was retrospectively investigated in 113 children in continuous first remission. Weight was examined at diagnosis up to 10 y after cessation of treatment. There was an increased prevalence of overweight after treatment for ALL which persisted over time. All treatment regimens included corticosteroid therapy, and 52 patients received additional cranial irradiation. Patients treated with and without cranial irradiation did not differ in weight gain, indicating that not cranial irradiation but corticosteroid therapy might explain weight gain in children treated for ALL. Dexamethasone was associated with a significant increase of weight at cessation of treatment. Patients treated with a combination of prednisone and dexamethasone had as a late effect the highest prevalence of obesity (44%). Gender or age at diagnosis were not related to weight gain.