Longitudinal studies of growth and endocrine function of children with AML transplanted with BUCY are limited. We report a cohort of 23 children with AML transplanted (15 autologous and eight allogeneic) following a single chemotherapy protocol and surviving at least 2 years after BMT. Busulfan was given as a single daily dose. Growth and endocrine function was evaluated yearly from one up to 10 years post transplant (median 4.9 years). The mean height standard deviation score (HtSDS) of the entire group decreased from 0.01 (s.e.m. +/- 0.25) at diagnosis to -0.38 (+/- 0.28) at BMT (P = 0.001). There was no statistically significant difference between HtSDS at BMT and yearly HtSDS from 1 to 5 years post BMT. There was no significant relationship between age at BMT and subsequent change in HtSDS. To date, five of six girls have needed sex steroid replacement. Six of 12 evaluable boys had abnormal gonadotrophins, but none required sex steroid replacement. Children with AML who undergo BMT with BUCY show no significant growth impairment, but gonadal dysfunction is prominent, particularly in girls. Bone Marrow Transplantation (2000).