Clinical and postoperative audiometric and tympanometric findings of otitis media with effusion managed at Seoul Paik Hospital, Inje Medical College were observed. The number of ears for clinical observation was 770 ears(503 patients) consisting of 500 ears(293 patients) in children and 274 ears(210 patients) in adults. Postoperative audiometric and tympanomanometric studies were performed in 409 ears(301 patients) which had middle ear fluid. The results of studies were as follows ; 1) 167 ears(70%) were MOM in children and 138 ears(80%) were SOM in adults. 212 patients(42%) were fell into the ages from 4 to 9 years and 318 patients(63%) visited our clinic from December through May. 2) In 134 ears of follow-up studies for pure tone audiometry postoperative hearing was restored within 20dB in children at speech range and high frequencies, but in adults a mild hearing impairment above 20dB remained at speech range and high frequencies. 3) Middle ear volume in 192 ears of follow-up was progressively increased in cases with a functioning ventilation tube except for several cases. 4) At the first visit postoperatively, eustachian tube function in 246 ears of follow-up showed either group 3 or 4 in most cases. 5) Eustachian tube function test at the last visit showed that the improvement of tubal function was 28.9% of 128 ears in children of follow-up and 17.3% of 52 ears in adults. During the follow-up the incidence of ears which had no change in eustachian tube function was almost same in both children and adults. 6) In normalized 70 ears which demonstrated tympanogram type A and positive acoustic reflex after spontaneous extrusion or removal of a ventilation tube, 52 out of 70 ears(72.9%) belonged to either group 2 or 3 and 43 ears(61.4%) showed marked increase of middle ear volume during follow-up study.