It is well known that the eustachian tube has the function of ventilation, clearance, and protection of the middle ear, contributing to the maintenance of normal hearing. After the opening of eustachian tube by contraction of the tensor veli palatini muscle, which pull the lateral lamina against the medial lamina, the eustachian tube may return to its original position by elasticity resulting from the recoil of elastic fiber, muscle itself, and other deformed soft tissues surrounding the tube. The maintenance of these factors, related to closing of the eustachian tube, has been regarded as one if important factors in the pathogenesis of otitis media. The topoanatomic study of elastic fibers of the eustachian tube which operates in opening and closing of the eustachian tube may provide insight, leading to an understanding of the nature and pathogenesis of the tube dysfunction. For evaluation of distribution of elastic fibers, we have stained rat eustachian tube with modified Weigert's method. The tubal cartilage has a considerable content of elastic tissue in all regions. The mesh of elastic fibers of rat eustachian tube is the most abundant at the hinge portion and the density gradually decreased in the middle portion. These finding suggest that elastic fibers may do an signficant role on the closure of the eustachian tube following its opening by contraction of tensor veli palatini muscle. It has thus believed to be and important factor in the mechanical properties of recoiling in closing of eustachian tube.