The exact contribution of growth hormone (GH) deficiency to the adverse growth outcome, in those receiving cranial irradiation (18–24 Gy) or total-body irradiation for haematological malignancies in childhood, remains difficult to disentangle as nearly always the cause of the growth disturbance is multifactorial: chemotherapy, graft-versus-host disease, hypothyroidism, and skeletal dysplasia may all impact on growth. There are few published data from which one can assess the efficacy of GH replacement on final height in those children who received cranial irradiation (18–24 Gy) and/or total-body irradiation; there is no evidence, however, of an increased risk of leukaemic relapse. Endocrine reassessment in the teenagers, who received cranial irradiation (18–24 Gy) for acute lymphoblastic leukaemia many years earlier, revealed a significant incidence of GH deficiency with the additional suggestion that many had been GH deficient for several years. This raises a number of important questions: What is the best way to organize long-term endocrine follow-up? How often should GH status be reassessed? What are the specific benefits of GH replacement in adult life for such individuals? These and other questions require further study.