Ethanolic fraction from edible mushroom, Russula albonigra, was tested for in vitro antioxidant activity, namely, DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, chelating effect on ferrous ions, reducing power and total antioxidant capacity assay and a quantitative estimation of putative antioxidant components like total phenol, flavonoid, β-carotene, lycopene and ascorbic acid was carried out. Findings showed that EC50 values were below 1 mg /ml except DPPH radical scavenging test. The extract exhibited 50% DPPH radical scavenging activity at only 1.8 mg /ml concentration. Estimated putative antioxidant components was in order of phenol > flavonoids > ascorbic acid > β-carotene> lycopene. Result implies that Russula albonigra can be a potential source of natural antioxidant which may be used as food suplement to treat various oxidative stress related diseases.