AIM:To provide rational evidence for the administration of warfarin in clinic by investigating the utilization of warfarin in our hospital.METHODS:By retrospective analysis,the prescription of warfarin in our hospital was obtained from November 2016 to February 2017 from the system for clinical pharmacist.The general situation of the inpatient,the diagnosis of disease,the use of warfarin,and the combination of drugs and the number of International Normalized Ratio (INR) were statistically and descriptively analyzed.RESULTS:In this investigation,200 patients were included,of whom 53％ were males and 47％ were females with an average age of (55.28 ± 13.56) years.Only 21％ of the average INR values reached the predicted range (2 ＜ INR ＜ 3) during hospitalization and the average dose of warfarin was (2.62 ± 0.60)mg.In patients with INR ＜ 2,there were 66.92％ of patients combined with more than one kind of drugs,which decreased the effect of warfarin.In patients with INR ＞ 3,there were 80％ of patients combined with more than one kind of drugs,which increased the effect of warfarin.CONCLUSION:The rate of warfarin compliance is low and the warfarin-drug interactions exert a great influence on the patients whose INR value did not reach the predicted range.Thus,to keep the drug safety of patients,more attention should be paid on drug interactions and direct personalized medicine using professional knowledge of pharmacy.