There has been said that Eustachian tube ventilatory function is deeply related to adenoidal hypertrophy, so the author evaluated E-tube function before and after adenoidectomy in 68 cases(136 ears) of children with normal intact ear drum. E-tube function in individuals with intact tympanic membrane can be simply determined by tympanometry using four kinds of maneuver, such as Toynbee, Valsalve, Inflation and Deflation test. And then the following results were obtained : 1) In 125 ears with type A of tympanogram, the incidence of the ears with normal E-tube ventilatory function was converted from 42(33.6%) to 94 ears(75.2%) after adenoidectomy. The cases with type C(10 ears) & type B(1 ear) showed E-tube obstruction. 2 of 10 ears with type C had improvement and 11 ear with type B had not improvement in E-tube ventilatory function postadenoidectomy. 2) The incidence of normal tube function ears was not increased as the A/N ratio became greater. 3) According to above results, it would appear that the adenoid mechanically obstructed the E-tube before adenoidectomy and after adenoidectomy the function had been converted to a more normal function.