The middle ear mucociliary system has been shown to have an important function in the clearance of effusions. Little is known, however, about its role in chronic suppurative otitis media (CSOM). The ciliary beat frequencies of middle ear mucosal biopsies and nasal brushings of 27 patients with CSOM were analysed using a computerized photometric technique. The ciliary beat frequency in the middle ear mucosa was significantly less than that in nasal mucosa. Frequency in ears of smoking patients was significantly lower compared with non-smoking patients. Nasal brushings were taken from 27 otherwise healthy age and sex-matched non-smoking controls and the ciliary beat frequency was very similar to nasal samples from patients with CSOM. Ear controls were obtained from otosclerotic patients undergoing tympanotomy and the beat frequency was significantly higher than in the ear of patients with CSOM. It is concluded that middle ear ciliary function is significantly reduced in CSOM, particularly in patients who smoke.