BACKGROUND: Warfarin is a widely used oral agent for anticoagulation therapy. Warfarin has a narrow therapeutic index and a wide variation in the interindividual therapeutic dosage. Recently, genotypes of CYP2C9 and VKORC1 have been found to account for 30-40% of the warfarin dosing variability, and a variety of commercial genotyping assays are being introduced. In this study, we evaluated the Verigene Warfarin Metabolism Nucleic Acid test (Verigene Warfarin assay; Nanosphere, USA) for its accuracy and clinical utility in genotyping CYP2C9*2, CYP2C9*3, and VKORC1 1173C>T. METHODS: We compared the Verigene Warfarin assay with direct sequencing for accuracy in determining the genotypes of CYP2C9*2, CYP2C9*3, and VKORC1 1173C>T using 50 patient samples and 3 commercial DNA samples with known genotypes. The method was also evaluated for turn-around time, hands-on time, and feasibility. RESULTS: The Verigene Warfarin assay demonstrated 100% accuracy for identifying CYP2C9*2, CYP2C9*3, and VKORC1 1173C>T. The turn-around time and hands-on time were 3 hr and 2 min, respectively. The no-call error rate at first attempt was estimated to be 2%. CONCLUSIONS: The Verigene Warfarin assay provides rapid and accurate genotype results. Considering there are only a few steps requiring manual intervention, it would be feasible to implement this assay even in clinical laboratories that lack considerable expertise in molecular diagnostics.