Objective To investigate the role of clinical pharmacists in warfarin therapy. Methods A total of 134 patients underwent prosthetic heart valve replacement and had warfarin for life from March 2013 to October 2013 in Fujian Medical University Union Hospital. All patients were equally divided into two groups (an intervention and a non-intervention group) crosswise by sequence. There were 67 patients in each group. The anticoagulant effects of the two groups were compared. Results There was no statistical difference in the patients' demographic information between the two groups. However, the time for the patients to reach the target international normalized ratio(INR) values for the first time (7.1±3.3 dvs. 10.5±5.0 d,P=0.000) and time of INR in the therapy range (46.3%±18.8%vs.19.0%±16.2%,P=0.000) during their hospitalization, proportion of time of under anticoagulation (47.5%±19.5%vs. 71.2%±22.9%,P=0.000), proportion of time of anticoagulation overdose (5.3%±8.2%vs. 9.9%±16.7%,P=0.002) were significantly different. While there was no statistical difference in postoperative hospitalization time between the two groups (19.9±6.6 dvs. 18.1±7.0 d,P=0.137). There were 4 patients (6.0%) with minor hemorrhage and no severe complication was found in the intervention group. There were seven patients (10.4%) with mild hemorrhage, two patients with stroke, one patient with mild pulmonary embolism, and severe complication rate of 4.5% in the non-intervention group. Conclusion With clinical pharmacists involved in the whole anticoagulation therapy progress of patients after mechanical heart valve replacement, the time to achieve the therapeutic window for the first time is effectively shorten, and the time of the INR value controlled in therapeutic range is highly improved during hospitalization time. Moreover, the patients' risk of thrombosis and bleeding is eventually reduced.