In a group of 37 patients (47 ears) expected middle ear effusion by otoscopic findings or detected the presence of fluid at myringotomy, the results of impedance audiometry by means of Teledyne impedance bridge (Model TA-ID) were observed. Tympanometric results indicated that type B tympanograms were occurred in 96% of ears and type As tympanogram with low compliance in 4%. We detected middle ear effusions in 85% of ears in the total group. Fluid was found in 84% of 45 ears with type B and in all of type As ears. The static compliance was typically low and the mean static compliance for ears with effusion was 0.105cc, ranging from 0.01cc to 0.3cc. The acoustic reflex could not be elicited about 90% in 40 ears with effusion. Exact percentage of acoustic reflex in the total group ranged from 89% at 500Hz to 91% at 4,000Hz. In a subgroup of 19 patients with unilateral middle ear effusion, the results showed that the acoustic reflex was present when sound was presented to the bad ear, but ws absent in almost ears when sound was presented to the good ear.