Growth hormone (GH) deficiency in adults is now recognized as a clinical syndrome with characteristic signs and symptoms. Numerous trials with daily subcutaneous biosynthetic human growth hormone (hGH) have been conducted in this patient group. Generally, improvements in insulin-like growth factor levels, decreases in total fat mass and increases in lean body mass are recorded with no overall effect on total body weight. Variable effects on serum cholesterol, bone mineral density and quality of life have also been reported. The true place of GH replacement therapy in adults has yet to be defined. Several questions relating to the dose, duration of treatment, long-term side-effects, quality of life changes and health economic implications of treatment still need to be assessed.