Clinical, audiometric and tympanometric findings of otitis media with effusion from Jan 1985 to Jun 1987 at St. Benedict Hospital in Pusan were observed. The results were followed : 1) Sex distribution showed 146 males(55%) and 120 females(45%). 2) The peak age was 6-10 years old(83 cases, 32.3%). 3) Bilateral effusion was 68% and unilateral was 32%. 4) The peak of seasonal distribution was winter(39.8%) 5) The most common chief complaint was hearing loss(66.9%). 6) Known etiologic factors were sinusitis 78 cases(29.3%), hypertrophy of tonsil and adenoid 31 cases(11.7%), nasal septal deviation 28 cases(10.5%), hypertrophy of tonsil and adenoid with sinusitis 25 cases(9.3%), allergic rhinitis 18 cases(6.8%), etc. 7) Myringotomy with tube insertion was performed in 169 ears. 8) Preoperative pure tone average was 21.2 dB. 9) In preoperative tympanogram, there were 8.3% with type As, 76.7% with type B and 15.0% with type C. 10) The natures of middle ear effusion were 15.2% with serous exudate, 62.8% with mucoid exudate and 22.0% with no fluid in 164 ears. 11) In postoperative E-Tube function test, there were 2.4% with good, 50.6% with fair and 47.0% with poor. 12) The changes of middle ear volume during postoperatively following period were 55.3% below 1.5 cc, 21.2% from 1.5 cc to 3.0 cc and 23.5% above 3.0 cc.