objective:to investigate the reversal effect of 4’－methylether－scutellarein(4’－m－s) on multidrug resistance in human choriocarcinoma jar/vp16 cell line. Methods:quantitative accumulation and efflux of rhodamine 123 (rh123),a p－glycoprotein(p－gp)substrate,were determined using a flow cytometric assay (fcm) for measuring p－gp function. Mdr1 mrna levels were detected by semi－quantitative reverse transcriptase－polymerase chain reaction (rt－pcr). The expressions of p－gp were analyzed by western blot and immunohistochemistry(ihc) method. Results:the results of fcm suggested that 20 μg/ml 4’－m－s could significantly increase the intracellular accumulation of rh123 in jar/vp16 cells. Rt－pcr and western blot results revealed that the expression levels of mdr1 mrna and p－gp protein were low in 4’－m－s treated cells. The ihc study showed that mild immunostaining for p－gp was seen in jar/vp16 cells when treated with 4’－m－s. Conclusion:the reversal effect of 4’－m－s in jar/vp16 cell may be related to regulating expression of mdr1/p－gp and increaseing intracellular concentration of chemotherapeutic drugs.