Two hundred patients who had been fitted with binaural hearing aids were chosen as subjects for a questionnaire survey to determine the factors which would influence the use of binaural hearing aids. From the analysis of the 16 factors used which included audiological, physical and social factors, the following results were obtained: (1) A significantly greater proportion of male patients used binaural hearing aids than female patients. (2) A significantly greater proportion of patients with a different hearing loss configuration in the two ears used binaural hearing aids as compared with those with a symmetrical hearing loss. (3) Frequent users of binaural hearing aids were males, who had had additional help to reduce their hearing disability, and had a more severe hearing loss in the better ear. The use of binaural hearing aids in noisy situations and in localising sounds was also investigated.