Transforming growth factor-β (TGF-β) has been shown to have a positive effect on in vitro fertilization (IVF) and has been reported to stimulate meiosis at follicular level in variety of species. The study was designed to determine the expression patterns of TGF-β1, TGF-β receptors type Ⅰ, Ⅱ and Smads gene in bovine oocytes and embryos. TGF-β1 and their receptors were observed in the unfertilized oocytes. TGF-β1 and type Ⅱ receptor were not expressed at the blastocyst stage, however, only type I receptor was exclusively observed at the same stage. The blastocyst stage, in particular, showed high levels of mRNA expression patterns containing a TGF-β type Ⅰ receptor. The mRNA expression pattern of Smad 2 at all stages of embryonic development was similar in all respect with TGF-β1 type I receptor. On the contrary, Smad 3 and 4 were expressed with high and low level mRNA at the blastocyst stage. In conclusion, it is suggested that TGF-β signaling may be regarded as an important entity during the preimplantation embryo development.