Many genetic variants have been shown to affect drug response through changes in drug efficacy and likelihood of adverse effects. Much of pharmacogenomic science has focused on discovering and clinically implementing single gene variants with large effect sizes. Given the increasing complexities of drug responses and their variability, a systems approach may be enabling for discovery of new biology in this area. Further, systems approaches may be useful in addressing challenges in moving these data to clinical implementation, including creation of predictive models of drug response phenotypes, improved clinical decision-making through complex biological models, improving strategies for integrating genomics into clinical practice, and evaluating the impact of implementation programs on public health. For decades, genetic variation has been clearly implicated as an important determinant in drug disposition and effects. 1 One of the promises of the completion of the human genome project is personalised medicine, one aspect of which is pharmacogenomics, or tailoring drug therapy to an individual's genetic makeup. 2 To date, the field has focused largely on the effect of individual genetic variants with large effect sizes. Extending this paradigm to large numbers of drugs will likely require consideration of the complex interplay of genetic, metabolic, environmental, and developmental factors on drug responses. 3 Enabling this type of analysis will be a framework that views drug response as a dynamic system and maps