Introduction & Objective: The diagnostic value of endoscopic and microscopic procedures for viewing different structures of middle ear has been widely assessed however, no published study is available for comparing the diagnostic value of them in chronic otitis media patients. The present study conducted to compare diagnostic value of these two procedures for assessment of middle ear normal structures and possible defects in these patients.

Materials & Methods: In a prospective descriptive analytical study, fifty eight consecutive pa-tients older than 15 years who suffered from chronic otitis media and were candidates for tympanoplasty with or without mastoidectomy were included into the study and underwent operation. After entering the middle ear by post auricular incision and elevation of a tym-panomeatal flap, and prior to surgery , the middle ear was first examined by an operating mi-croscope in different bed and microscope positions and by performing gentle maneuvers on the head and then was reevaluated using a rigid 0 & 30 degree sinoscope. The visible areas of middle ear were separately noted.

Results: Structures of epitympanum, posterior mesotympanum, and hypotympanum structures were more visible using endoscope compared with microscope (P<0.05). Among different parts of mesotympanum, oval window, round window, and eustachian tube were more observable by the former procedure (P<0.05). Regarding evaluation of the ossicular chain mo-bility and reflexes of round window as well as ossicular chain erosions by microscope and endoscope, no significant difference was detected (P>0.05).

Conclusion: Endoscopic and microscopic procedures had similar diagnostic values to view ossicular chain mobility and reflexes of round window as well as to detect ossicular chain erosions, but different anatomical parts and more hidden pits of the middle ear such as epitympanum, posterior mesotympanum, and hypotympanum are more visible by an endoscopic tool.In case of pathologic conditions, endoscopic approach is recommended for better observation and adequate evaluation of the location before and after the removal of the lesion.