BACKGROUND Extracellular heat shock protein 70 and peptide complexes (eHSP70/HSP70-PCs) regulate a variety of biological behaviors in tumor cells. Whether eHSP70/HSP70-PCs are involved in the epithelial-mesenchymal transition (EMT) of tumor cells remains unclear. AIMS To determine the effects of eHSP70/HSP70-PCs on EMT of hepatocarcinoma cells. METHODS The expressions of E-cadherin, HSP70, α-smooth muscle actin protein (α-SMA) and p-p38 were detected immunohistochemically in liver cancer samples. Immunofluorescence, western blotting and real-time RT-PCR methods were used to analyze the effects of eHSP70/HSP70-PCs on the expressions of E-cadherin, α-SMA and p38/MAPK in vivo. RESULTS HSP70, E-cadherin, α-SMA and p-p38 were elevated in hepatocellular carcinoma tissues. The expression of HSP70 was positively correlated with malignant differentiated liver carcinoma. The expressions of HSP70, α-SMA and p-p38 correlated with recurrence-free survival after resection. eHSP70/HSP70-PCs significantly promoted the expressions of α-SMA and p-p38 and reduced the expressions of E-cadherin in vivo. The effect was inhibited by SB203580. CONCLUSION The expressions of HSP70, E-cadherin, α-SMA and p-p38 may represent indicators of malignant potential and could discriminate the malignant degree of liver cancer. eHSP70/HSP70-PCs play an important role in the EMT of hepatocellular carcinoma via the p38/MAPK pathway.