Evaluation of: Tham LS, Goh BC, Nafziger Aet al.:A warfarin-dosing model in Asians that uses single nucleotide polymorphisms in vitamin K epoxide reductase complex and cytochrome P450 2C9.Clin. Pharmacol. Ther.80, 346–355 (2006) . Large interindividual variability exists in warfarin dose requirements and the development of genotype-guided dosing algorithms that accurately predict warfarin doses is of considerable interest. Tham and colleagues used specific CYP2C9 and VKORC1 polymorphisms, along with clinical factors, to build an algorithm to accurately estimate warfarin doses in a multi-ethnic Asian population. The final model accounted for 60.2% of the overall variability in warfarin dose requirements. In a separate validation cohort, the model accurately estimated warfarin doses with a correlation of 0.73 between actual and model-predicted doses. The next step in warfarin pharmacogenomic research is to take warfarin dosing algorithms, such as the one developed in this study, and use them in prospective, randomized studies in order to determine whether genotype-guided warfarin dosing is better than the traditional care approach.