Antioxidant activity of methanolic extract of Hypsizygus ulmarius was studied for its free radical scavenging property on different models. The inhibition percentage increased in dose dependent manner. IC50 values for scavenging of 2,2-Diphenyl-1-Picrylhydrazyl (DPPH), nitric oxide(NO), hydroxyl(OH), superoxide(SO) and ferric reducing antioxidant power (FRAP) assay were found to be 74, 410, 450, 640, 152μg/ml respectively. This was compared with standards like ascorbic acid, quercetin and Butylated Hydroxytolune (BHT). The result presented has a good antioxidant property against free radical and it may serve as a good pharmacological property