Recent research has confirmed previous clinical suspicion that adults with pituitary disease and growth hormone (GH) deficiency have impaired physical and psychological performance even in the presence of adequate adrenal, thyroid and gonadal hormone replacement therapy. This GH deficiency syndrome is characterised particularly by impaired psychological well-being, abnormal body composition with increased abdominal adiposity, reduced strength and exercise capacity, reduced basal metabolic rate, reduced bone density and an elevation in total and low density lipoprotein cholesterol. This latter finding may be important in the context of the observed increase in cardiovascular mortality rates of GH-deficient adults. GH replacement therapy administered as a once-daily subcutaneous injection can restore a near normal quality of life to many of these patients, although there is as yet no evidence that this treatment reduces mortality. Adverse effects of GH therapy are few and have probably been overstated due to excessive doses used in the initial studies. These can be minimised by starting at a low initial dose and increasing gradually while monitoring clinical response and serum insulin-like growth factor-1 values. All adults with GH deficiency should now be considered for GH replacement therapy.