Decreases in growth hormone (GH) and insulin-like growth factor I occur with age, in addition to oestrogen deficiency in women and a reduction in the levels of testosterone in men. These age-related hormonal changes may contribute to reductions in lean body mass, muscle strength and cardiac endurance, which can be partially reversed in elderly people with GH treatment, and testosterone supplements and oestrogen/progestin hormone replacement therapy in men and women, respectively. These treatments are, however, thought to have potentially serious adverse effects. We conducted a study to evaluate the separate and interactive effects of GH and sex steroids on body composition, muscle strength and cardiac endurance as well as the rate of adverse events in healthy elderly people. The results of the study showed that although there were beneficial effects with GH and sex steroid treatment, a high percentage of adverse effects occurred after 26 weeks of treatment, demonstrating a need for more research on the safety of hormonal therapy in the elderly population.