Adhesion formed between tendon and its sheath after repair often impairs functional recovery. There have been many attempts to reduce adhesion around a repaired tendon, but most results have been unsatisfactory or impractical in clinical application. Moreover, most attempts were focused on extrinsic tendon healing. whereas studies on the intrinsic tendon healing are sacrce in the literature. We have previously reported that fibrotic tendon adhesion after repair was decreased by decorin, a natural inhibitor of TGF-beta. Accordingly, the serial tensile strength was measured after complete tensection and repair of the tendon severance in order to confirm the effect of decorin inhibition of intrinsic healing capability. Forty White Leghorn chickens were subject to complete transection and repair of the third toe flexor digitorum profundus tendon in Zone II. In the experimental group, 0.5ml of diluted decorin(50microgram/ml) was injected around the repaired site, and the same volume of saline solution in the control group. Tendons were harvested at 1, 3, 5 and 7 weeks. The disrupting force of the repair site was analyzed using tensiometry(LLOYD LR 30K, U.K). The tensile strength of repaired tendon was similar in both groups for all postoperative periods. This indicates that intrinsic healing proceeds normally within the decorin group in spite of the blockade of TGF-betaactivity. Decorin, a natural inhibitor of TGF-beta, showed a significant inhibitory effect on reducing post-repair tendon adhesions, without disruption of intrinsic healing in the chicken flexor tendon injury model. Therefore, decorin is expected to be a useful agent for preventnion on tendon adhesion after the repair in clinical usage.