The increased availability of growth hormone (GH) in the mid-1980s, as a result of advances in recombinant DNA techniques, has allowed research into the use of this hormone at physiological dosage, as replacement therapy for adults with GH deficiency (GHD) and at pharmacological dosages as a possible therapeutic agent, for a number of disease states. GHD adults have increased body fat and reduced muscle mass and consequently, reduced strength and exercise tolerance. In addition, they are osteopenic, have unfavourable cardiac risk factors and impaired quality of life. In these individuals, replacing GH reverses these anomalies, although it may not alter the reduced insulin-sensitivity. A proportion of adults with GHD perceive a dramatic improvement in their well-being, energy levels and mood following replacement. GH has protein and osteoanabolic, lipolytic and antinatriuretic properties. GH has been considered for the therapeutic treatment of frailty associated with ageing, osteoporosis, morbid obesity, cardiac failure, major thermal injury and various acute and chronic catabolic conditions. Initial small, uncontrolled studies for many of these clinical problems suggested a beneficial effect of GH, although, later placebo-controlled studies have not observed such dramatic effects. Furthermore, with a recent publication demonstrating an approximate 2-fold increase in mortality in critically ill patients receiving large doses of GH, the use of GH should remain in the realms of replacement therapy and research, until there are significant advances in our understanding.