© 2014 Taylor & Francis. This study was conducted to estimate the antioxidant activities, biochemical properties and biological activities of one of the entomopathogenic fungi, Cordyceps sinensis. Analysis of fungal metabolites indicated that the most abundant free sugar was glucose; the highest component of organic acids was citric acid from 10-day culture medium and the glutamate was the predominant amino acid observed from 3-day culture medium. Maximum total polyphenols and flavonoids were detected in the 15-day culture medium. For cytotoxicity test, three cancer cell lines, HepG2 (liver), MCF-7 (breast) and A549 (lung) were used. The IC50 values of the highest toxicity of HepG2 cell lines were observed from 10-day cultured medium, whereas the highest toxicity of MCF-7 and A549 was observed on 5-day cultured medium. This is the first study reporting on the strong antioxidant and cytotoxic potential of C. sinensis. Culture medium of C. sinensis may thus be used as an effective antioxidant and anticancer treatment of natural origin.