Scar production and neuroma formation at nerve graft coaptation sites may limit axonal regeneration and impair functional outcome. Transforming growth factor [beta ] (TGF-[beta ]) is a family of growth factors that is involved in scar formation, wound healing, and nerve regeneration. Fifteen adult Sprague-Dawley rats underwent autogenous nerve grafting. The nerve grafts were analyzed by in situ hybridization to determine the temporal and spatial expression of TGF-[beta ]1 and TGF-[beta ]3 messenger RNA (mRNA). The grafted nerves showed increased expression of TGF-[beta ]1 and TGF-[beta ]3 mRNA in the nerve and the surrounding connective tissue during the first postoperative week. These data suggest that modulation of TGF-[beta ] levels in the first postoperative week may be effective in helping to control scar formation and improve nerve regeneration. (J Hand Surg 2001;26A:1082[ndash ]1087.