Consumption of mushroom has increased remarkably because of their desirable aroma, taste and high nutritional content. This study was undertaken to measure and compare the antioxidant activity, total phenolic content (TPC) and total flavonoid content (TFC) of Agaricus bisporous (white button mushroom) and Agaricus brasiliensis (Brazilian mushroom) in aqueous and 60% ethanol extract. Results showed that button mushroom (21.47 ± 0.48 mg GAE/g of dry weight) had significant higher TPC in aqueous whereas Brazilian mushroom (12.50 ± 0.22 mg GAE/g of dry weight) had significant higher TPC in 60% ethanol (p< 0.05). In terms of TFC, Brazilian mushroom had higher content than button mushroom in both types of solvents. For FRAP assay, Brazilian mushroom had significantly higher total antioxidant activity than the button mushroom in 60% ethanol (p < 0.05) but opposite trend with aqueous. For DPPH radical scavenging activity, Brazilian mushroom (60% ethanol) had the lowest EC50 value, followed by button mushroom (60% ethanol), Brazilian mushroom (aqueous) and button mushroom (aqueous). Pearson correlation test (p < 0.05) showed strong positive correlation between TPC and FRAP assay in both extracts (r = 0.969 for 60% ethanol extract; r = 0.973 for aqueous extract). For TFC, there was a strong positive, correlation with FRAP assay (r = 0.985) in aqueous extract. In conclusion, high antioxidant activity in ethanol extract of mushrooms due to presence of phenolic content can potentially be used as a source of natural antioxidants.