The ACCF/AHA Clopidogrel Clinical Alert expertly summarizes the issues surrounding clopi- dogrel and the use of genotype testing, as well as the potential for routine platelet function testing.20 The FDA label revision does not mandate testing for CYP2C19 genotypes or overall platelet function.14 The revi- sion serves to warn clinicians that certain patient subgroups may exhibit reduced clopidogrel-mediated platelet inhibi- tion and emphasizes that clinicians should be aware of alternative treatment strategies to tailor alternative thera- pies when appropriate. A number of commercially available genetic test kits will identify the presence of 1 of the loss-of-function CYP2C19 alleles, but these tests are expensive and not routinely covered by most insurance policies. Additionally, there are no prospective studies that demonstrate that the routine use of these tests coupled with modification of antiplatelet therapy improves clinical outcomes or reduces subsequent clinical events. A recent meta-analysis demonstrated an association between the CYP2C19 genotype and clopidogrel responsiveness but no significant association of genotype with cardiovascular events.31 Several ongoing studies are examining whether genotype assess- ment with attendant alteration in antiplatelet therapy for those with loss-of-function alleles can improve clinical outcomes. On the basis of the current evidence, it is difficult to strongly recommend genotype testing routinely in patients with ACS, but it might be considered on a case-by-case basis, especially in patients who experience recurrent ACS events despite ongoing therapy with clopidogrel. Some argue that clinicians should consider routine testing of platelet function, especially in patients undergoing high- risk PCI,20 to maximize efficacy while maintaining safety. Again, no completed prospective studies have examined such an approach to guide such a sweeping change in clinical management. 