Recent studies have suggested that leptin plays an important role in reproduction. Ob-R is expressed in the murine embryo, and is suggested to play a role in embryo development, although contradictory results have been reported. In the present study, Ob-R expression was observed both at themRNAand protein levels in porcine early embryos.We have also demonstrated that leptin is produced in the porcine oviduct, making it spatially available to interact with its receptor during preimplantation development. When included at 10 ng/ml in embryo culture medium, leptin significantly increased the proportion of cleaved embryos (P < 0.01). At day 7 of in vitro culture, leptin at 10 and 100 ng/ml increased the proportion of embryos reaching the blastocyst stage (P < 0.01). We have previously observed that leptin increases oocyte maturation in vitro, and here we report that inclusion of leptin in both IVM and embryo culture medium further increased blastocyst development (P <0.05), compared to when leptin was included in the embryo culture alone, suggesting leptin has a synergistic role on both oocyte maturation and preimplantation embryo development.  The study suggest that leptin plays a positive role in the development of porcine preimplantation embryos. In addition to adding to knowledge on regulation of early embryo development, these results may also have clinical applications. In the pig, the current success rate of IVF and nuclear transfer techniques remains low. The finding that the inclusion of leptin in IVM and embryo culture mediums enhances early development suggests that leptin may aid in the optimization of these techniques, possibly leading to improved success rates.