The past decade of pharmacogenomics was driven by the sequencing of the human genome to create ever denser maps of genetic variations for studying the diversity across individuals. Today, genotyping technology is available at a fraction of the cost of what it was 10 years ago and many pharmacogenomic variations have been studied in detail. Still, we are only starting to gain an understanding of how pharmacogenomic-guided drug therapy affects clinical outcomes: real-world studies that demonstrate the clinical effectiveness and address the economic implications of pharmacogenomics are needed to help decide when and how to implement pharmacogenomics in clinical practice, how to regulate pharmacogenomic testing and how the healthcare system will integrate this new science into an environment of rapidly increasing cost.