The etiology of the recurrence of acute otitis media is not thoroughly understood. Recently, abnormal functions of neutrophils have been regarded as the cause of recurrent infections, and a few papers dealt with defective chemotactic responses of neutrophils in patients with recurrent otitis media. With the in-vitro agarose plate technique, neutrophil chemotaxis and random migration were measured in 20 children with recurrent otitis media to yield a significantly decreased chemotactic index compared with age-matched controls. Patients with other recurrent infections, such as recurrent parotitis and recurrent tonsillitis, showed a normal chemotactic index. Other children who had not only recurrent otitis media, but also systemic manifestations, showed an extremely low chemotactic index and revealed either defective phagocytic activity or deficiency of IgA. Defective chemotactic response may be one of the essential factors causing repeated attacks of middle ear infection.