Eustachain tube function was examined by the inflation-deflation test in 25 patients (29 ears) with otitis media chronica (OMC). In comparison with four normal controls, both passive and active ventilation functions of the tube in OMC were impaired, especially active ventilation. Patients with otorrhea showed more impairment of both active and passive ventilation function than did those with dry ears. Patients treated with tympanoplasty type III or IV showed more impaired active ventilation function than did those treated with tympanoplasty type I. These results indicate that the degree of impairment of Eustachian tube function is nearly proportional to the degree of pathological change in OMC.