As a clinical test, direct observation of the middle ear should be ideally performed without any surgical intervention such as myringotomy. This paper reports a newly invented superfine fiberscope which makes it possible to insert through the eustachan tube, and direct views of the middle ear structures on normal subjects and patients. The patients were of a small cholesteatoma and traumatic dislocation of the ossicular chain. All of them were tested with local anesthesia in outpatient clinic.This superfine fiberscope was of great value in observing of middle ear structures as a diagnostic instruments, as that no surgical intervention was necessary in the procedure.