The effect of thiol compounds on development and intracellular glutathione(GSH) concentrations of bovine embryos produced by in vitro maturation and in vitro fertilization(IVM/IVF) was examined in CRlaa medium with or without $eta$-mercaptoethanol(0, 10, 25 and 50$mu$MME) and cysteamine(0, 25, 50 and 75 $mu$M). Numbers of cells comprising blastocysts were also counted using double fluorescence stain and the total glutathione levels(oxidized and reduced form) of morula and blastocyst embryos were than measured by an enzymatic method. Following routine IVM/IVF procedures oocytes and zygotes were cultured for 40 to 44h in CRlaa medium. Then 2 to 8-cell embyos had cumulus cell removed and were allotted randomly to the experimental medium. In Experiment 1, the proportion of embryos developing to and beyond morulae stages in 0, 10, 25 and 50 $mu$M $eta$-ME was 42.9%, 50.0%, 53.7% and 65.6%, respectively. Fifty $mu$M $eta$-ME group was significantly higher than those of any other groups (P<0.05). In Experiment 2, the percentages of embryos developed beyond morulae stages in 0, 25, 50 and 75 $mu$M cysteamine was 42.9%, 40.4%, 60.0% and 59.2%, respectively. Fifty and 75$mu$M cysteamine groups were significantly higher than in 0 and 25 $mu$M cysteamine groups, but all of culture medium containing cysteamine(52.6%) was not significantly difference in control group(42.9%). In Experiment 3, the intracellular GSH concentrations of morulae and blastocyst embryos in 0 and 50 $mu$M $eta$-ME was 42.4 pM and 44.9 pM, 49.5 pM and 67.8 pM, respectively. Morulae embryos were not difference, but blastocyst embryos were significantly difference between treatments(P<0.05). In Experiment 4, the intracellular GSH concentrations of morulae in CRlaa with or without cysteamine were 39.8 pM and 45.6 pM, and blastocysts were 59.3 pM and 66.8 pM, respectively. Cell numbers of blastocysts were similar to in all experimental groups. These experiments indicate that thiol compounds can increase the proportion of embryos that developing to and beyond morulae stage and the intracellular GSH concentrations.