Cancer may impinge on puberty either directly through a mass lesion effect on the reproductive axis or indirectly through hormones secreted by tumours, for example human chorionic gonadotrophin, or weight loss, or the actual presence of a chronic disease process per se. The more frequent pubertal problems faced by children with cancer are due to the impact of treatment either on the central nervous system, the hypothalamic-pituitary axis or the gonad; in this review, we concentrate on these complications and their potential management.