Chaga mushroom (Inonotus obliquus) extract has been known to have therapeutic effects, such as anti-inflammatory, hepato-protective, anti-oxidant and anti-tumor effect. In this study, we evaluated the effects of Chaga extract on the cytotoxic actions of cisplatin in HepG2 hepatoma cells. The viability of the HepG2 cells was decreased to 10% at 3 ${mu}M$ cisplatin and to 20% at 500 ${mu}g$/ml Chaga extract as measured by the MTT assay. The viability of HepG2 cells co-treated with cisplatin (3 ${mu}M$) and Chaga extract (500 ${mu}g$/ml) was decreased to 50% in compared with the control cells. The cytotoxicity of two drugs was revealed as apoptosis characterized by the chromatic condensation, nuclear fragmentation and the cleavage of pro caspase-3 in HepG2 cells. Also, the cells treated with combination of two drugs showed synergistically the loss of mitochondrial membrane potential and increase of intracellular ROS levels. Therefore, these results suggest that the combination treatment of cisplatin and Chaga extract induces apoptotic cell death in HepG2 cells and has more potential anti-tumor effect than cisplatin alone.