Growth hormone (GH) deficiency in adults has only recently been recognised as a clinically important syndrome which is associated with increased morbidity and probably also with increased mortality. Its presence leads to many unfavourable changes in body composition (increased fat mass and decreased lean mass), lipid metabolism, bone mass and may worsen quality of life. In many patients the disease may be either asymptomatic or present with relatively moderate subjective symptoms. The signs and symptoms, if evident, however, are often too common to have a diagnostic value without a suggestive clinical context. Diagnosis of GH deficiency in adults is more difficult than in children. It should be always confirmed by the results of biochemical, especially provocative, tests, among which the insulin tolerance test is considered the test of choice. Long-term recombinant GH administration in GH-deficient adults improves body composition, muscle strength, quality of life, bone mass and density, and lipoprotein pattern. In this review article we discuss the causes, clinical picture, diagnosis and treatment of GH in adults and provide the reader with some practical guidance concerning dealing with a patient suffering from this disorder.