Objective To observe transforming growth factor-?1(TGF-?1) in chicken callus. Methods The right humerus fracture models of 16 New Roman hens, at the age of 6-month old, about 1.75kg in weight, were established under no germ operational condition. TGF-?1 of the tissue samples procured from callus on 3d,6d,10d and 15d of fracture healing were examined by immunohistochemical method. Results Histochemical study shows that the immunostaining of TGF-?1 exists in blood cells on 3d, connective tissue cells and extracellular matrix on 6d, cartilage on 10d and 15d. Compared with that on 3d, the expression of TGF-?1 increased markedly on 6d, 10d and 15d of fracture healing(P