Pharmacogenetics blends important components of the disciplines of genetics and pharmacology, and aims to describe the influence of inheritance on variable drug response. This review provides an overview of the history and current status of pharmacogenetics. The role of genetics in variable drug response is now firmly established. To apply this information to the clinical setting, more sophisticated methods, such as a multiple candidate gene approach, or genomic approaches, are likely to be needed. Most drugs will require additional research if their use is be guided by a patient's genetic make-up. However, it seems that the potential for pharmacogenetics to improve the clinical outcomes of numerous drug therapies will be realized, and will represent an important biomedical advance in the post-genomics era.