Objective : This study investigated the apoptotic effect and its mechanism of Radix Aconiti (RA) extract and aconitine, which is a major constituent of RA, in HepG2 human hepatoma cells. Methods : We used MTT and DNA fragmentation assay to investigate cell viability and apoptotic effect on RA extract-treated HepG2 cells. In addition, to clarify the mechanism of RA extract-induced apoptosis, we applied caspase-3 enzyme activity assay and Western blotting method on poly-(ADP-ribose) polymerase (PARP) protein expression. Results : Treatment with RA extract resulted in the decrease of cell viability, and this effect was caused from apoptosis as confirmed by discontinuous fragmentation of DNA in HepG2 cells, but aconitine did not. Also, RA extract-treated HepG2 cells induced the activation of caspase-3 enzyme activity in time- and dose-dependent manners, which was accompanied by the cleavage of 116 kD PARP to 85 kD product. Conclusions : These results suggest that the apoptotic effects of RA extract on HepG2 cells could not be explained by aconitine. Additionally, RA extract induced apoptosis in hepatoma cells through caspase-3 activation and subsequent PARP cleavage.