Longitudinal growth was studied in children treated for non-Hodgkin's lymphoma (NHL). The aim of the study was to compare these children's growth velocity with findings in a previous study we performed on age-matched children with acute lymphoblastic leukemia (ALL) who received cranial irradiation. Nine children with NHL with an onset time of treatment between 4 and 9 years of age (mean 6.5 years) were studied with annual body measurements taken from the time of the diagnosis and thereafter annually during the following 4 years. None of the children received cranial irradiation. During the first treatment year a significantly low mean height velocity was observed (-1.4 standard deviation score [SDS]) for the NHL group. The consecutive two 1 year periods showed a normalization of the mean height velocity. For the group of children with ALL, there was a more prominent negative effect on height during the first 2 years of treatment than for the NHL group in the present study. After the cessation of therapy, the children with NHL showed a reduced catch-up growth compared with the children with ALL. The explanation offered is that cranial irradiation has a heavier impact on growth than chemotherapy during the first 2 years of treatment, but an intense chemotherapy during the maintenance period could have a considerable impact in blunting growth.