Twenty-three temporal bones from 14 patients who had undergone stapedectomy more than 15 years (the longest, 28 years) preceding death were studied microscopically. Although a foreign body reaction was still found in the ears with a polyethylene prosthesis, it was seldom found in the ears with a wire or Teflon prosthesis. As the resorption of the incus was not severe, it was suggested that it occurred in the early stage of post-stapedectomy and the structural condition of the incus and prosthesis was stable for a long time (even over 15 years) after stapedectomy. In all ears, the grafts on the oval window continued to be the adequate barrier between the middle ear and inner ear. Even though cupping of the graft membrane was frequently found, it seemed not to disturb the sound conduction. The depth of the cupping was correlated somewhat with the thickness of the graft.