Tympanometry has become routine in clinical diagnosis of middle ear diseases since early 1970s. However, low frequency tympanometry is relatively insensitive to many lesions that affect the ossicular chain. This study on 20 patients with bilateral conductive hearing loss compares the pre-operative multifrequency tympanometry test results with their operative data. There is an accuracy of 78% in diagnosis of otosclerosis and 72% in diagnosis of ossicular discontinuity using this test.