Three cases of pituitary adenomas with infra-sellar extension into the nasopharynx and the nasal cavities are reported. The clinical signs were epistaxis, nasal obstruction, painful sinuses and purulent rhinorrhoea. The initial diagnostic hypothesis was that of a carcinoma of the nasopharynx or the sinuses in all three cases. The diagnosis was made by histological examination and measurement of plasma hormone levels. These cases highlight the difficulty in the diagnosis of such tumours due to their misleading clinical, radiological and histological features.