Many injuries of the hand have been occurred in these days because of frequent industrial hazards and frequent handling of tools in modern civilizing life. A voluminous amount of literature has been recently concerned with many problems and questions posed by tendon surgery. Many investigations have been devoted to discussion of suture materials, tendon suturing, grafting, healing, rate of healing, nutrition and related clinical and laboratory endeavors. Whatever the material, the aim of tendon suture is not only restoration of a strong mechanical union but also sliding function of the tendon. Thus the question has always been after what delay active mobilization can be allowed or encouraged. If immobilization allows fibroblasts to invade the tendon extremities and form a scar mass, its prolong leads to adhesion and loss of normal sliding. On the other hand, one can admit that early passive or active mobilization, even if only over a short distance may distend the adherences and transform them into a kind of mesotenon assuring a better sliding function. Before permiting early motion, several factors must be considered such as tensile strength of the suture material, holding power of the suture for the tnedon, bulkiness of the repair and stress that must be withstood. Thus it is the purpose of this study to analysis and comparing of tensile strength and morphological changes in the healing process of tendon tissues by different suturing methods. For this study deep flexor tendon on third toe of adult chicken with an initial weight of about 2Kg was used. The animals were divided into 4 sutured groups which including different suturing methods. Suturing methods used were interrupted suture, Bunnels lace suture, Kessler suture and end-weave anastomosis, which have been applied frequently in tendon surgery. All suture material used were the same size 4-0 Ethilon which has least tissue reaction but high strength. In the animals, after the sharp dissection of the distal portion of the deep flexor tendon on third toe, the tendon stumps were approximated and sutured by 4 different methods. Then a long leg cast in the position of flexion of the foot and ankle joint was applied. On operation day and fifth, tenth, fourteenth and twenty-first postoperative day; the animals were sacrified and the specimens were gained. The measurement of the tensile strength of the sutured tendon was performed through the use of force transducer with the recording of polygraph for permitting continous monitoring of a progressively increasing load until the failure of tendon repair. Specimens stained with hematoxylin-eosin and Massontrichrome stain were observed during 42 days after operation. The findings are as follows. 1. The tensile strength of sutured tendon groups using interrupted suture, Kessler suture, and end-weave anastomosis were reduced maximally on fifth postoperative fay and the tensile strength of Bunnel's lace suture group was reduced maximally on tenth postoperative day. Thereafter the strength was increased progressively on entire experimental groups. 2. The tensile strength of end-weave anastomosis group was the strongest among all experimental groups during experimental period. 3. Just after the repairs of injured tendon, the order of strength was Bunnel. Kessler and inerrupted suture but the strength was nearly approximated on 21st day. 4. The morphological healing process of interrupted and Kessler suture were better than that of Nunnel and end-weave suture. From these morphological and physical results, it is suggested that Kessler suture is better suturing method in tendon repair.