Apoptotic processes have been associated with cancer and neurodegenerative diseases such as Alzheimer's disease, Parkinson's disease etc. beta-Alanyl-L-histidine (L-carnosine), occurring abundantly in skeletal muscles has been suggested to possess antioxidative activity. We investigated whether L-carnosine prevents 12-O-tetradecanoylphorbol-13-acetate (TPA)- or hydrogen peroxide (H2O2)-induced apoptosis involving mitochondria in the v-myc transformed rat liver epithelial cells (WB-myc cells). L-Carnosine prevented both TPA- and H2O2-induced DNA fragmentation, the loss of mitochondrial membrane potentials and blocked the release of cytochrome c into cytosol. Subsequently, the cleavages of poly (ADP-ribose) polymerase were significantly reduced in L-carnosine-treated cells. However, western blotting analysis revealed that p53 protein level did not change for 12h after TPA- and H2O2-treatment. Therefore, these results suggested that L-carnosine, an antioxidant, protected both H2O2- and TPA-induced apoptosis through mitochondrial pathways.