Effectiveness of impedance audiometry in diagnosing serous otitis media in children was examined in this study. The impedance test battery was performed on seventy-six ears of pre-myringotomy children (Mean age: 4.6 years). The status of the middle ear was assessed by the operating physician during surgery, and impedance results were correlated with the operative findings. Middle ear effusion was the variable that most influenced impedance results. Acoustic reflex threshold and tympanometry were the most sensitive tests in predicting effusion. Multiple correlations between these tests and the presence of significant effusion indicated that both measures together are diagnostically more sensitive than either test alone. Also, reflex measurement at one test frequency is as accurate a predictor of effusion as reflex measurement at all frequencies.