Objective To investigate the efficacy and safety of warfarin anticoagulation in Chinese elderly patients based on vitamin K epoxide reductase complex 1 (VKORC1) and cytochrome P450 2C9 (CYP2C9) genetic polymorphisms.Methods Clinical data of 41 elderly patients with initial anticoagulation therapy in our emergency department and respiratory department were collected.Patients were divided into observation group (n=20,patients treated with warfarin based on genetic polymorphisms) and control group (n =21,patients treated based on clinical experience).The international normalized ratio (INR),the time of INR stabilized within target range (2.0-3.0) and the incidence of bleeding episodes in 6-month follow up were compared between groups.Results INR within target range at day 3,4,5 and 7 were 0.0％,42.1％,52.6％,68.4％ in observation group and 0.0％,10.0％,25.0％,35.0％ in control group,respectively.There were significant differences in INR within target range at day 4,7 between the two groups (both P＜0.05),while no significant difference was found in INR within target range at day 5 (P＞0.05).The time of INR stabilized within target range was shorter in observation group than in control group [(9.5±2.4) d vs.(12.3± 4.8) d,P＜0.05].Bleeding complication occurred in 3 patients in observation group and 5 patients in control group,and there was no significant difference between the two groups.Conclusions Warfarin therapy based on VKORC1 and CYP2C9 gene polymorphisms may shorten the time of first INR reaching the target value and INR within target range in elderly patients.However,the risk of bleeding complications should be alerted.