Conclusion: Chronic suppurative otitis media causes some disturbance to the chorda tympani nerve (CTN), which may affect the facial nerve. It is not possible to perform a biopsy of the main truncus of the facial nerve, therefore studies of the CTN might show possible pathologic or physiologic changes of the facial nerve in the future. Objectives: The specific aim of this study was to investigate the effects of chronic suppurative otitis media on the CTN. Methods: The tympanic segments of CTNs were collected for ultrastructural investigations in patients with chronic suppurative otitis media who underwent canal wall-down tympanoplasty. The study population comprised 10 patients, 7 males, 3 females; the age range was 16-66 years, and the mean age was 38. Qualitative and semiquantitative evaluations were performed on the specimens of CTN by electron microscopy. Results: Our histopathologic examinations showed that there were changes of varying severity in all the CTNs such as scarcity of unmyelinated nerve fibers, Schwann cell nucleus condensation, scarcity of Schwann cell cytoplasm, adaxonal vacuolation and edema, myelin sheath disintegration, shrunken electron-dense axoplasm, increased collagen fibers, adaxonal circular lamellar complex, interstitial edema, and vacuolation of Schwann cell cytoplasm.