 The standardization of translating CYP2D6 genotype to metabolize a phenotype across clinical laboratories offering pharmacogenetic testing and PGX clinical practice guidelines is not uniform, leading to discordant cytochrome P for 52D6, CYP2D6, phenotype assignments and inconsistent therapeutic recommendations. A modified Delphi method was used to obtain consensus for a uniform system among international CYP2D6 experts, resulting in 82% of the experts agreeing to the final CYP2D6 genotype to phenotype translation method. Broad adoption of this method by guideline developers and clinical laboratories will result in more consistent interpretation of CYP2D6 genotype. This article was authored by Kelly E. Cordell, Ketrin Sankl, Michelle Welcorillo, and others.