Ligament and tendon prostheses have all suffered because of failure of the particular material that has used in the past. Various materials, including, silk, nylon, Dacron, and combinstions of other synthetic substances, have all enjoyed temporary vogues and have vogues and have all passed out of habitual use because of collapse of the material employed. In an attempt to find an alternative material for use as a tendon or ligament prosthesis, a fundamentally new approach to the problem has been used, namely, that of tendon ligament induction. Carbon fiber has an attraction as a biologic implant because of its inherently inert nature when used in the pure form. Within recent years, it has been possible to manufacture filamentous carbon fiber of high purity and constant filament size, and this material has been examined as a tendon and ligament prosthesis. Both achilles tendons of 14 adult Korean rabbits were replsced with carbon fiber reinforced epoxies(CFRE, it was developed in department of chemical engineering, Chungnam national university, Daejeon, Korea) after artificially rupture, and serial histologic examination of neotendon formations and biologic responces in vivo were done during 8 weeks. The results obtained were as followings ;1. Hemorrhage and inflammatory reactions were observed at 2–3 weeks after operations. 2. Foreign body reactions were developed at 4 weeks after operation, also observed proliferations of foreign body giant cells and histiocytes. 3. Fibroblasts were increased at 4 weeks after operation, and most severe poliferations at 5–6 weeks. 4. Foreign body reactions and fibroblasts were markedly decreased at 7–8 weeks after operation, and examination of the collagen itself showed it to be closely similar to that found on the normsl side.5. Thus, it appeared that the carbon fiber initially acted as a tendon prosthesis.