Having noted symptomatic osteoporotic vertebral collapse in young adult survivors of childhood malignancy, bone mineral density (BMD) was examined at three sites by dual-energy X-ray absorptiometry in 64 patients treated in childhood for intracranial malignancy (group 1; n = 21) or acute leukaemia (group 2; n = 43). Patients in group 1 were selected for growth hormone deficiency (GHD) by auxological and biochemical criteria before the end of puberty (Tanner stage V). Seven patients (six men; mean (+/- SEM) age at study, 28.0 +/- 2.9 years; mean age at diagnosis, 8.7 +/- 1.5 years) in this group had been treated with human pituitary growth hormone (GH) for 1-12 years; and 14 patients (nine men; mean age at study, 26.8 +/- 1.0 years; mean age at diagnosis, 10.7 +/- 1.4 years) had not received GH. Bone densities in group 1 were normal in the GH-treated patients at the femoral neck (98.4 +/- 3.8% of control), lumbar spine (100.4 +/- 6.1% of control) and Ward's triangle (101.0 +/- 6.1% of control) but markedly reduced in the untreated group (femoral neck, 81.2 +/- 2.6% of control (p = 0.002); lumbar spine, 79.1 +/- 4.1% of control (p = 0.04); Ward's triangle, 80.1 +/- 3.6% of control (p = 0.01)). The majority of patients in group 2 had been treated for acute lymphoblastic leukaemia (ALL) and were in three subgroups.(ABSTRACT TRUNCATED AT 250 WORDS)