Pegvisomant is the only available member of a new class of drugs: the growth hormone receptor antagonists. It has a proven efficacy in antagonising the effects of growth hormone in acromegalic patients that is better than any of the currently available treatment modalities. Its safety profile looks encouraging, although more long-term safety data are needed. Potential indications for pegvisomant in diabetology and oncology again looks very promising, but the optimism is almost entirely built upon favourable data from pre-clinical studies, whereas data from human studies are not yet available.