Weight for height of 92 patients (51 girls and 41 boys) treated for acute lymphoblastic leukemia (ALL) was evaluated in a longitudinal study. Fifty-four patients received cranial irradiation (CI) with a dose of 18 or 24 Gy and 38 patients did not receive CI. Seventy-seven patients were treated according to a normal-risk protocol and 15 patients received more intensive chemotherapy according to a high-risk protocol. In most of the patients the duration of follow-up was 12 years for irradiated patients and 4.5 years for the nonirradiated patients. Thirty of 92 patients were treated according to a protocol without CI, but with a difference in the use of corticosteroids: 19 patients received dexamethasone during the remission-induction and maintenance treatment and 11 patients received prednisone. The influence of dexamethasone vs. prednisone, sex, CI and high-dose vs. low-dose chemotherapy on weight for height was evaluated. Patients who received dexamethasone showed a significant increase in weight for height immediately after the start of therapy. In patients who received CI, weight for height significantly increased after the first year of treatment. The overweight in these patients persisted during the whole follow-up period. The weight for height of patients treated with prednisone and of patients who did not receive CI was below the mean of the normal population during treatment but was not different from normal after cessation of therapy. No difference in weight gain was seen between boys and girls and between patients who were treated with high vs. normal-risk protocols.