Harford has explained the diagnostic value of the impedance audiometry on the evaluation of eustachian tube dysfunction. Using electro-acoustic bridge (Madsen ZO 70), we have studied 35 patients who had ratracted eardrums and stenotic eustachian tube with mild conductive deafness and 4 patients of patulous eustachian tubes on catheterization and compared the results with that of the 50 normal persons. During the tests, examines were asked to perform Valsalva maneuver and the movements of balance meter needle during the maneuver were also checked. The results are as follows ; 1) Tympanogram in normal cases showed all typeA curve. Static compliance was 0.3~1.3cc (Mean 0.68). Lateral swing of balance meter needle during Valsalva maneuver was 1.0~4.0 (Mean 2.4). 2) Tympanogram in patients of patulous eustachian tube showed all type A curve. Static compliance was 1.2~1.5cc (Mean 1.34cc). Lateral swing of needle during Valsalva maneuver were all above 5.0. 3) Tympanogram in 35 cases (55 ears) of stenotic eustachian tube showed type A curve in 6 ears, type B curve in 12 ears, type C curve in 37 ears. Static compliance was 0.05~1.20cc (Mean 0.45cc). Lateral swing of needle during Valsalva maneuver was 0.0~1.5 (Mean 0.41).