Pharmacogenomics is emerging as an important component both in facilitating new drug development and in improving the utility of existing chemotherapeutic agents. Both candidate gene and genome-wide approaches have been used to identify genetic markers associated with chemotherapeutic response and/or toxicity. New molecular targeted agents have been designed based on a sophisticated understanding of the molecular alterations defining cancers. Over the next decade, the translation of these findings into clinical practice, as well as functional studies of genetic variants, is likely to take center stage. More comprehensive evaluation of the human genome, including the examination of rare SNPs, copy number variations, tandem repeats and epigenetic effects, will further improve our understanding of the relationship between genetics and drug response.