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Objective Our aim is to assess the performance of warfarin pharmacogenetic algorithms in patients post mechanical cardiac valve replacement under low dose warfarin anticoagulation. Methods Based on the specified standard, from January 2012 to October 2013, 107 patients of Yijishan Hospital of Wannan Medical College were enrolled in the study. The target international normalized ratio (INR) ranging from 1.6 to 2.5 post surgery of mechanical cardiac valve replacement were set under low dose warfarin anticoagulation. All the patients' CYP2C9 and VKORC1 genetic polymorphisms were detected by PCR-RELP and sequencing technology, and their doses of warfarin were adjusted by the results of INR. The patients were stratified into 3 groups according to the dose range:lower dose group (≤1.5 mg/d), intermediate dose group (1.5~4.5 mg/d) and higher dose group (≥4.5 mg/d). Then the predictive warfarin doses were calculated by international warfarin pharmaeogenetics consortium (IWPC) algorithm, the performance of the algorithm was evaluated by the mean absolute error (MAE) between warfarin predicted doses and actual stable doses, and the percentage of patients whose predicted doses within ideal doses (20% of their actual stable doses), over doses and under doses were compared. As well, the predicted warfarin doses were also regressed on stable doses, from which we obtain R2 values. Results MAE between warfarin predicted doses and stable doses was (0.89±0.62) mg/d with R2=0.325. The percentage of warfarin predicted doses within ideal doses was 42.06%, and the percentage within ideal doses in higher group was 50.00%, which was higher than in intermediate dose group (43.75%) and lower dose group (11.11%). Conclusion The performance of IWPC algorithm used in warfarin anticoagulation dose assessment in Chinese Han population is infinite, the pharmacogenetic algorithms suitable for the Chinese Han population with low dose warfarin anticoagulation need to be further studied and verified clinically. [ABSTRACT FROM AUTHOR]