The TNF-related apoptosis-inducing ligand (TRAIL) has recently been implicated in the death of hepatocytes under infectious but not normal conditions. Our previous studies showed that both the whole HBV genome and its HBx protein enhanced TRAIL-induced hepatocyte apoptosis. We report here that preS2-containing viral proteins are also potent regulators of TRAIL-induced apoptosis. HBV-transfected hepatoma cell line, HepG2.2.15, pretreated with antisense oligonucleotide against preS2 gene, showed a lower sensitivity towards TRAIL-induced apoptosis. However, this effect might not be related with the expression level of TRAIL receptors. These results establish that besides HBx, preS2 viral proteins are also involved in enhancing TRAIL-induced hepatocyte apoptosis. The novel role of preS2 would be useful to further unravel the mechanisms of imbalanced apoptosis during HBV infection and provides a potential therapeutic target for HBV-related diseases.