Research studies in both cardiac and stroke medicine have demonstrated significantly worse outcomes in patients treated with clopidogrel who are poor metabolisers of CYP2C19 and major guidelines have advocated the role of genetic testing in these specialities.5, 7 Research into the impact of CYP2C19 alleles in vascular surgery is much more limited but does suggest an association between poor metabolisers of CYP2C19 and adverse outcomes in patients taking clopidogrel.8 9. This evidence concerns the gene CYP2C19 and Stroke.