Clinically nonfunctioning pituitary adenomas represent one-third of pituitary tumours submitted to surgery. Symptoms consist mainly of visual impairment and there is no evidence of hormonal hypersecretion. Most nonfunctioning pituitary adenomas express genes of glycoprotein hormone subunit(s), and release these hormones in vitro. Thirty per cent of tumours do not synthesize any recognizable pituitary hormones. The first-line treatment is surgery, with the aim of removing as much of the tumour as possible and of reducing visual defects without excessive risks 80% of patients show visual improvement postoperatively. Tumour remnants exist in 30 to 50% of cases; radiation therapy is applied when tumour removal is incomplete. Recurrence of tumour and visual signs and/or an increase in the size of the tumour is noted in about 20% of cases even after radiation therapy. Medical treatment is used when tumour resection is impossible or hazardous. Long-term dopamine agonist treatment in a few cases can induce rapid and partial improvement and small decrease in tumour size in about 15%. Somatostatin analogues can induce an early visual improvement in limited cases, but little visible tumour shrinkage. GnRH analogues have been used in gonadotrophin-secreting tumours; super agonists seem unable to reduce secretion and tumour size.