The antioxidant potential of the ethanolic extracts from 11 different strains of Pleurotus ostreatus were comparatively investigated against hydroxyl radical, DPPH (1,1-Diphenyl-2-picrylhydrazyl) radical, superoxide radical, reducing power and ferrous ion chelating ability. Total phenolic contents were also determined. Significant correlation was found between the total phenolic content and the antioxidant capacity of the ethanolic extracts of all the strains. Cellular damage caused by reactive oxygen species has been implicated in several diseases and hence antioxidants have significant importance in human health. Results of this study showed that, ethanolic extract of the strain MTCCNo.1804 has maximum antioxidant property and may be utilized as a promising source of therapeutics.