Objective  To explore the reversal effect of tetrandrine(Tet) in combination with droloxifene(Drol) on multidrug resistant cell line K562/A02.Method  The cytotoxicities of daunorubicin(DNR) were assayed by 3(4,5?dimethylthiazole?2?yl)?2,5?diphenyl  tetrazolium bromide(MTT) method.Results  The cytotoxicities of DNR to K562/A02 were enhanced by 1?μmol·L    -1   Tet or 5?μmol·L    -1   Drol.Their IC    50   was (7.28±2.06)mg·L    -1   and(7.58±3.44) mg·L    -1  ,respectively.Their reversal effect on K562/A02 was found to be 2.94 and 2.82 times,respectively.But IC    50   of combined Tet and Drol was (1.66±0.41) mg·L    -1  ;its reverse effect increased up to 12.9 times.Conclusion  Multidrug resistance(MDR) may be partially reversed by Tet or Drol,but the combination of Tet and Drol shows a greater synergistic reversal interaction.