Why do different patients with the exact same disease symptoms respond differently to the same drug? Understanding such variations at the molecular level would be very valuable because it would allow drug makers to tailor a therapy to the individual's specific needs. Pharmacogenomics is the name that has been recently given to any drug-discovery platform that attempts to address this problem. While the concepts of individual variation at the molecular level are not new (for over 40 years pharmacology has approached this same problem from a toxicological point of view), the platform technologies that propose to successfully implement this concept have all been developed within the past four years.