Growth was studied in 88 long-term survivors of acute lymphoblastic leukemia who had been treated with three different regimens of therapy. The following time periods were evaluated: (1) during therapy; (2) between the end of therapy and the onset of puberty, and (3) between the onset of puberty and the most recent observation. We found: (1) a reduction of height SDS during therapy, related to the irradiation dose used; no significant effect of the duration of the therapy could be established; (2) a normal growth rate during the second time period studied for the total group, but a further decrease in height SDS for those found to be growth hormone deficient after therapy (47%), and (3) a further decrease in height SDS during puberty. The timing of puberty in the female patients was normal. We conclude that in patients treated for acute lymphoblastic leukemia, growth impairment has several components, different in timing and mechanism.