Arteria stapedialis in the rat was studied in healthy rats and in experimental otitis media with effusion (OME). The mean diameters of the vessel was calculated to approximately 460 μm (healthy) and 430 μm (otitic) (no significant difference). The tunica intima consisted of an endothelium and a well-developed elastica interna. The tunica media was composed of 2–3 layers of smooth muscle cells. The adventitia was thicker than the media and consisted of bundles of collagan fibers. The artery in the middle ear cavity was quite naked covered only with the middle ear mucosa. The stapedial artery did not appear to be involved in the production of effusion in experimentally induced