The goal of individualized drug therapy requires physicians to be able to accurately predict an individual's response to a drug. Both genetic and environmental factors are known to influence drug response. 'Pharmacogenetics' is the study of the role of inheritance in variation in drug response phenotypes. Pharmacogenetics is now moving genome-wide to become 'pharmacogenomics', resulting in the recognition of novel biomarkers for individual variation in drug response. This article reviews the development, promise and challenges facing pharmacogenomics, using examples of drugs used to treat or prevent cardiovascular disease.