Objective To research the efficacy and safety of olanzapine combined with a triple antiemetic regimen for the prevention of CINV in patients undergoing multiple days of cisplatin chemotherapy.Methods Forty-six patients receiving three days of cisplatin chemotherapy from September 2018 to April 2023 were divided into an observation group and a control group,with 23 patients in each group.The control group was given the conventional triple antiemetic regimen,and the observation group additionally added olanzapine 5 mg D1~5 orally each night.To observe the occurrence of D1~7 nausea and vomiting in both groups after chemotherapy and the adverse effects after using olanzapine.Results Comparison of acute CINV incidence and complete remission rate,delayed CINV incidence and complete remission rate,and full-stage incidence and complete remission rate between the two groups was statistically significant(P<0.05).The incidence of dizziness was 4.3%(1/23)and drowsiness was 4.3%(1/23)during the use of olanzapine in the observation group,and five patients in the observation group had improved sleep after the application of olanzapine.Conclusion Olanzapine combined with a triple antiemetic regimen reduces acute and delayed CINV induced by a three-day cisplatin-containing chemotherapy regimen and the adverse effects were tolerable.