Antrodia camphorata (A. camphorata) is well known in Taiwan as a traditional Chinese medicine, and it has been shown to exhibit antioxidant and anticancer effects. In this study, therefore, its ability to induce apoptosis in cultured MCF-7 breast cancer cells was studied. Treatment of the MCF-7 cells with a variety of concentrations of the fermented culture broth of A. camphorata (25-150 microg/ml) resulted in dose- and time-dependent sequences of events marked by apoptosis, as shown by loss of cell viability, chromatin condensation, internucleosomal DNA fragmentation, and sub-G1 phase accumulation. Furthermore, apoptosis in the MCF-7 cells was accompanied by the release of cytochrome c, activation of caspase 3, and specific proteolytic cleavage of poly (ADP-ribose) polymerase (PARP). Although, the A. camphorata-induced apoptosis was associated with Bax protein levels, negligible Bcl-2 reduction was observed. Interestingly, A. camphorata induced dose-dependent reactive oxygen species (ROS) generation in MCF-7 cells. Analysis of the data suggests that A. camphorata exerts antiproliferative action and growth inhibition on MCF-7 cells through apoptosis induction, and that it may have anticancer properties valuable for application in drug products.