The objective of the present study was to elucidate the fundamental mechanism of bovine oviduct epithelial cell (BOEC) co-culture on developmental capacity of bovine IVM/IVF embryos and to determine whether or not melatonin acts as an antioxidant in BOEC culture and subsequent embryo development. These studies examined the effects of melatonin against NO-induced oxidative stress on cell viability, lipid peroxidation (LPO) and the expression of antioxidant genes (CuZnSOD, MnSOD and Catalase) or apoptosis genes (Bcl-2, Caspase-3 and Bax) during BOECs culture. We also evaluated the developmental rates of bovine IVM/IVF embryos with BOEC co-culture, which were pre-treated with melatonin ($1,000;{mu}M$) in the presence or absence of sodium nitroprusside (SNP, $1,000;{mu}M$) for 24 h. Cell viability in BOECs treated with SNP (50-$2,000;{mu}M$) decreased while melatonin addition (1-$1,000;{mu}M$) increased viability in a dose-dependent manner. Cell viability in melatonin plus SNP ($1,000;{mu}M$) gradually recovered according to increasing melatonin addition (1-$1,000;{mu}M$). The LPO products were measured by thiobarbituric acid (TBA) reaction for malondialdehyde (MDA). Addition of melatonin in BOEC culture indicated a dose-dependent decrease of MDA, and in the SNP group among BOECs treated with SNP or melatonin plus SNP groups MDA was significantly increased compared with SNP plus melatonin groups (p<0.05). In expression of apoptosis or antioxidant genes detected by RT-PCR, Bcl-2 and antioxidant genes were detected in melatonin or melatonin plus SNP groups, while Caspase-3 and Bax genes were only found in the SNP group. When bovine IVM/IVF embryos were cultured for 6-7 days under the BOEC co-culture system pre-treated with melatonin in the presence or absence of SNP, the highest developmental ability to blastocysts was obtained in the $1,000;{mu}M$ melatonin group. These results suggest that melatonin has an anti-oxidative effect against NO-induced oxidative stress on cell viability of BOECs and on the developmental competence of bovine IVM/IVF embryo co-culture with BOEC.