Compliant tube, which is forced to open and close easily by low pressure, is a new concept of the eustachian tube abnormality. This abnormal condition is supposed to be one of the causes of various middle ear diseases like otitis media with effusion and cholesteatoma. In this report we performed four different eustachian tube function tests (inflation-deflation test, forced response test, eustachian tube function in pressure chamber test and negative pressure test) before and after cutting the third branch of trigeminal nerve, using rats. Finally we succeeded to make the experimental compliant tube.