Recently an attempt to repair the perforated drum has become quite common. However, as regards the questions what histopathological finding could be observed in both the tympanic membrane and the transplanted graft, and whether such a graft would cover up the perforations to take place of the tympanic membrane, or the graft would play only a role aiding regeneration of the tympanic membrane, there are still no histopathological studies. In order to solve these questions central perforations in pars tensa of the tympanic membrane of rabbits were made with injection needles and these perforations were repaired by transplanting free skin or buccal mucous membrane graft from the same animals, and the following conclusion were obtained. 1. Of the 14 ears transplanted with free skin graft, in 7 cases (50%) the transplantation was successful, namely, the free skin graft adhered to the tympanic membrane. Of 10 ears receiving the transplantation of buccal mucous membrane graft it was successful in two cases. (20%). 2. By the fifth to sixth day after the transplantation, there could be observed no marked changes in the skin graft or in the buccal mucous membrane graft, and also no fibrous adhesion could be observed between the transplanted graft and the tympanic membrane. 3. On the seventh day it was observed that transplantation began to take hold of itself between the transplanted free skin graft or the buccal mucous membrane graft and the tympanic membrane. 4. In the case where the transplantation had come to take hold of itself, the epithelium of the mucous membrane of tympanic membrane, extending along the interior side of the transplanted graft, closed the perforation, and the submucous tissue of tympanic membrane adhered directly to the connective tissue of the skin graft or the buccal mucous membrane graft. 5. When the adhesion takes place, the grafted skin or the buccal mucous membrane loses their morphological characteristics. As the times go on, the structure of the grafted tissues is used to change metaplasically to the tissue which reminds us of the lamina propria of the tympanic membrane. In this instance the new tympanic membrane is quite thick at the beginning but it gradually becomes thinner.