The study was conducted with ethanolic extract of edible mushroom, Lentinus connatus, which was tested for total phenol, flavonoid, β-carotene, lycopene and ascorbic acid and in vitro antioxidant activity in terms of superoxide anion and DPPH radical scavenging activity. Some other biochemical assays including chelating effect of ferrous ion, reducing power and total antioxidant capacity assay were conducted with varying concentrations. The data showed that EC50 values were between 1 – 2 mg /ml except superoxide and DPPH radical scavenging tests. Phenol was present in the highest amount followed by other bioactive components (flavonoids, ascorbic acid, β carotene and lycopene in the respective order). The results obtained reveal that L. connatus can be a potential source of natural antioxidant which may be used to treat various oxidative stress related diseases.