The statural growth of 85 prepubertal children treated for acute lymphoblastic leukemia was evaluated in a longitudinal study over 4.5 years. Patients were divided into three groups according to central nervous system prophylaxis: 37 patients received cranial irradiation with a dose of 24 Gy, 15 received a dose of 18 Gy, and 33 were not irradiated. According to the risk of leukemia, patients were divided into normal-risk (n = 74) and high-risk (n = 11) groups. The duration of treatment was 2 years, during which all patients showed growth retardation. The relative standard deviation score for height declined from 0 to -0.7 for the irradiated patients and from 0 to -0.2 for the non-irradiated group (P = 0.0001). There was no difference in growth pattern between cranial irradiation with 18 versus 24 Gy and chemotherapeutic treatment according to high-risk versus normal-risk protocols. However, a negative synergistic effect of more intensive chemotherapy and cranial irradiation on growth was demonstrated.