Objective To explore the increasing risk of herpes zoster and its possible mechanisms for hematologic disorders treated with arsenic trioxide (ATO). Methods The cases were divided into study group (with ATO) and control group (without ATO). The incidence rate of herpes zoster was compared between the two groups, and then the average cycles of chemotherapy were compared between the patients complicated with herpes zoster or not in study group. Results The rate of herpes zoster was significantly higher in study group than that in control group (χ2 =4.492, P =0.034). The rates of herpes zoster were 23.95 % (23/96) in study group and 7.89 % (3/38) in control groups. Patients in study group with herpes zoster had received 7.60 cycles and those without herpes zoster 7.72 cycles of chemotherapy on average (Z=0.976, P=0.296).Conclusion The risk of herpes zoster complication in hematologic disorders was increased after ATO treatment which probably activated varicella-zoster virus.