The study of the potential alpha (α)-tocopherol antioxidants towards garut sheep (Ovis aries) oocyte maturation and viability post-cryopreservation using slow freezing method has been studied. This study aimed to determine and evaluate the optimal concentration of adding alpha (α)-tocopherol towards oocyte in vitro maturation and viability post-cryopreservation. A total of 138 oocytes which have A and B qualities, were matured in TCM-199 medium with the addition of alpha (α)-tocopherol antioxidants at concentrations of 0 μM, 100 μM, 150 μM, and 200 μM. Oocytes from in vitro maturation are then cryopreserved and the maturity and viability was observed. Observation of oocyte maturation was based on the formation of the polar body I. Observation of oocytes viability used Hoechst and propidium iodide dyes. This experiment showed that there was no significant (P > 0.05) difference between concentrations, but the results of developments in concentration of 150 μM have the highest percentage of oocyte maturation (88.57 %) and viability (82.86 %). In conclusion, the presence of 150 μM alpha (α)-tocopherol was the optimal concentration that is able to maintain the oocyte membrane stability post-cryopreservation.