Patients with adult onset otitis media with effusion are generally subjected to an examination and biopsy of the nasopharynx under a general anaesthetic to exclude a neoplasm of the post-nasal space. The likelihood in Caucasian countries of a tumour being detected has not been clearly defined. The clinical features of the 55 patients with nasopharyngeal malignancy presenting to the Glasgow hospitals since 1970 have been analysed, and the incidence of malignancy in all adults presenting with middle ear effusions has been assessed in order to define the association of the 2 conditions. The study confirmed that while an effusion is commonly associated with a nasopharyngeal tumour (33%), in only 2% was it the sole clinical manifestation at the initial consultation. In addition, adults with effusions, but without other symptoms and signs suggestive of a tumour, are unlikely to harbour a tumour, the incidence in this review being 0.4%. Therefore, an examination and biopsy of the nasopharynx under general anaesthesia is likely to give a very low yield of additional information in cases of isolated middle ear effusions in adults, and the cost effectiveness of the procedure should be questioned.