Abstract. Egra S, Kusuma IW, Arung ET, Kuspradini H. 2018. The potential of white-oyster mushroom (Pleurotus ostreatus) as antimicrobial and natural antioxidant. Biofarmasi J Nat Prod Biochem 16: 17-23. White-oyster mushroom (Pleurotus ostreatus) is a favorite meal in Indonesia. Previously this fungus was known as a useless plant, but after the nutrition is known, everything changes. People tried to cultivate it because the nutrients contents are very good for body health. Therefore, to support this added value in the field of health, especially antimicrobials and antioxidants, this research needs to be done. This research used successive extraction with hexane solvent, acetate ethyl, ethanol, water, and crude ethanol by antimicrobial assay, antioxidants assay (DPPH), total antioxidant content, total phenolic content. The highest results on barrier antimicrobial test which occurred against Candida albicans bacteria was 47.60 % with 100 ppm concentration. While, on antimicrobial assay using Propionibacterium acnes bacteria, there was no significant inhibition. Regarding the antioxidant test against DPPH, the result showed the occurrence of free radical by 25 % on water extraction at the concentration of 100 ppm. Continuously, the total antioxidant content assay showed the ethyl acetate had the highest value of 368.708 mg gae/g. The results of the total content phenolic assay showed the solvent hexane had the value of 78.495 mg gae/g. These findings indicated that mushroom has an active phenolic compound with no contribution to impede its working on Candida albicans assay.