Multifrequency tympanograms were recorded from 76 ears of 43 children affected by otitis media with effusion (OME) and 90 ears of normal-hearing children to obtain data for resonance frequency (RF) and changes in phase angle. There was found to be a statistically significant decrease (p < 0.01) in both RF values and change in phase angle in ears with OME compared to normative data. This decrease may be interpreted by considering OME as a mass pathology. Multiple-frequency tympanometry seems to be a useful method for determining the effect of various middle-ear pathologies on the mechano-acoustical status of the middle-ear system.