In this study, synergic effects of MEM vitamins (MEMv) and beta-mercaptoethanol (bME) supplemented to porcine maturation medium on reactive oxygen species (ROS) of oocytes and embryos, and apoptosis of blastocysts were determined. Cumulus-oocyte- complexes (COCs) were allocated into four treatment groups: 0.05X MEMv, 25 uM bME, 0.05X MEMv + 25 uM bME or a group without MEMv + bME. In experiment 1, COCs were cultured in four respective treatment groups based on NCSU-23 medium for 44 h at 39℃ in a 5% CO2 atmosphere. We evaluated ROS of oocytes. In experiment 2, COCs were cultured in four respective treatment groups and then were fertilized in vitro (IVF) or activated by chemical or electrical method. We determined ROS of early stage embryos (2 cell-4 cells) and apoptosis of blastocysts. DCHFDA for ROS level and TdT-mediated dUTP nick end labelling (TUNEL) for apoptosis were used. As a result, ROS level of oocytes was not significant difference among experimental groups. In early stage embryos produced by IVF, MEMv + bME group showed significantly lower ROS level than that of control group (p<0.05). Level of apoptosis in blastocysts of the MEMv + bME group was significantly lower than that of the control group (p<0.05). In early stage embryos produced by chemical activation, ROS level of MEMv + bME group was significantly lower than that of bME group (p<0.05) without significant difference with those of control and MEMv group. Level of apoptosis in blastocysts in the MEMv + bME group was significantly lower than that of the control group (p<0.05). In early stage embryos produced by electrical activation, ROS level of MEMv + bME group was significantly lower than that of control (p<0.05). However, apoptosis level of blastocyst was not significant difference among experimental groups. In conclusion, the present study indicates that the addition of MEM vitamins and betamercaptoethanol during in vitro maturation is able to alleviate the production of ROS and apoptosis.