Abstract: OBJECTIVE To investigate the clinical efficacy and safety of gene polymorphism guiding the individualized administration of warfarin in patients with venous thrombosis. METHODS A prospective cohort study was conducted to establish two cohorts, the genotyped guided group and fixed dose group. The initial warfarin dose of the patients in the genotyped guided group was based on the results of warfarin-related gene polymorphism detection, and IWPC model was used to formulate initial warfarin administration plan. The initial warfarin dose of the fixed dose group was 3 mg·d^-1. Pathophysiological parameters of the enrolled patients were collected and a three-months follow-up was carried out. The clinical efficacy and adverse reactions were compared between the two groups. RESULTS The time to reach the target international standardization ratio(INR) after warfarin treatment in the gene administration group(5.65±2.30)d was faster than that in the fixed dose group(8.51±3.97)d(P<0.001). After 2 weeks and 4 weeks of warfarin use, the time in therapeutic range(TTR) of the gene administration group reached 73.00% and 78.26%, respectively, significantly higher than that of the fixed dose group(TTR 58.11% and 64.67%)(P=0.001, P<0.001). However, the difference of TTR after 4 weeks between the two groups was no statistically significant. The incidence of minor bleeding events in the gene administration group was lower than that in the fixed dose group(P<0.05), but the differences of major bleeding events and the abnormal INR value(INR ≥ 4.0) were not statistically significant. CONCLUSION The clinical efficacy of warfarin in gene administration group is better than that in fixed dose group, and the incidence of small bleeding events was less than that in fixed dose group.