Objective To investigate the effect of extracts from Periplaneta americana L.on reversing MDR in HepG2/ADM.Methods HepG2/ADM was induced by continuous stepwise exposer to ADM.To investigate the effect of extractive from Periplaneta americana L.on drug resistance-associated protein( P-gp、MRP、LRP和BCRP) by immunocytochemical method and RT-PCR method.Results HepG2/ADM cells to ADM shows a strong multiple drug resistance that is 10.4 times,For DDP,5-FU showed weak resistance.The extractive from Periplaneta americana L.can cut the expression of P-gp and MRP1 protein in HepG2/ADM from immunocytochemical method,and it has statistically significant.The extractive from Periplaneta americana L.can cut the expression of P-gp gene,and it has statistically significant.Conclusion The extract from Periplaneta americana L.can effectively reverse MDR in HepG2/ADM,which targets for P-gp and MRP1 protein and P-gp gene of HepG2/ADM cells.