Abstract： Objective To explore the mechanisms of apoptosis induced by arsenic trioxide and amifostine in human acute promyelocytic leukemia cell lines HL-60 in vitro.Methods HL-60 cells were treated with different concentrations of arsenic trioxide alone and combined with amifostine.The inhibitory ratio of the ceils were measured by MTT assay.and the expression of Survivin Was detected by semiquantitate RT-PCR.Results Proliferation of HL-60 cells exposed to arsenic trioxide dwpped down with increasing dose of the dmg and this effect Was significantly hisher when arsenic trioxide Was used in combination with amifostine.Furthermore.there was a more significant decrease in Survivin expression in HL-60 cells treated with arsenic trioxide in combination with amifostine as compared to the cells treated only with arsenic trioxide.Conclusion Arsenic trioxide induced HL-60 cells to undergo apoptosis by downregulating the expression of Survivin. Amifostine enhanced the sensitivity of HL-60 cells to arsenic trioxide by downregulating the expression of Survivin,thus promoting apoptosis effect.