Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine. The purpose of this study was to evaluate the ability of aqueous extract from A. camphorata mycelia to protect normal human erythrocytes against oxidative damage in vitro. Oxidative hemolysis and lipid/protein peroxidation of erythrocytes induced by the aqueous peroxyl radical [2,2'-Azobis(2-amidinopropane) dihydrochloride, AAPH] were suppressed by A. camphorata mycelia in a time-and concentration-dependent manner. A. camphorata mycelia also prevented the depletion of cytosolic antioxidant glutathione (GSH) and ATP in erythrocytes. Moreover, cultured human endothelial cell damage induced by AAPH was suppressed by A. camphorata mycelia. Interestingly, A. camphorata mycelia exhibited significant cytotoxicity against leukemia HL-60 cells but not against cultured human endothelial cells. These results imply that A. camphorata mycelia may have protective antioxidant and anticancer properties.