Abstract: Harringtonine(HT),a domestic antitumor drug extracted from Cephalotaxus hainanensis Li showed high chemotherapeutic efficacy on human acute granulocytic leukemia and acutemyelocytic leukemia in clinics.Apoptosis of HL-60 cells can be induced by HT effectively; but forcells resistant to harringtonine,apoptosis can not be induced, even if the drug(HT)concentration isover 100 times of IC₅₀0 value. Although apoptosis occurred when its multidrugs resistance had beenreversed by verapamil, compared with sensitive HL-60 cells, the time at which apoptosis happeneddelaved and the drug dosage increased. All these suggest that apoptotic resistance might be one of themarks of drug resistance in tumor cells, and apoptosis related factors could play a role in the formation of multidrug resistance.