The Human Genome Project has catalyzed the emergence of a new approach to biology termed systems biology. Systems biology analyzes all the interrelationships of the elements in a biological system, rather than studying them one at a time, as has been the modus operandi in biology for the past 30 years. This systems approach has also emerged in the context of the view biology is an informational science and the development of high- throughput tools for capturing biological information and powerful new computational tools for analyzing it. The application of systems approaches to medicine will lead to the rise of predictive, preventive, and personalized medicine over the next 15-20 years, giving rise to a total transformation in how medicine is practiced. I will discuss these issues and note along the way several mathematical and/or computational challenges they pose. Biographical Sketch Dr. Leroy Hood is recognized as one of the world's leading scientists in molecular biotechnology and genomics. A passionate and dedicated researcher, he holds numerous patents and awards for his scientific breakthroughs and prides himself on his life-long commitment to making science accessible and understandable to the general public, especially children. One of his foremost goals is bringing hands-on, inquiry-based science to K-12 classrooms. Dr. Hood earned an M.D. from Johns Hopkins University in 1964 and a Ph.D. in biochemistry from the California Institute of Technology in 1968. Since then, his research has focused on the study of molecular immunology and biotechnology. His interests also include autoimmune diseases, cancer biology and mammalian development. Dr. Hood has published more than 600 peer-reviewed papers and co-authored textbooks in biochemistry, immunology, molecular biology and genetics. He also co-edited "Code of Codes," a book discussing scientific, social and ethical issues raised by genetic research. Dr. Hood is a member of the National Academy of Sciences, the American Philosophical Society, and the American Association of Arts and Sciences. His professional career began at Caltech, where he and colleagues pioneered four instruments, the DNA and protein synthesizers and sequencers, that constitute the technological foundation for contemporary molecular biology. One of the instruments has revolutionized genomics by allowing the rapid automated sequencing of DNA. Dr. Hood also was one of the first advocates and is a key player in the Human Genome Project - the quest to decipher the sequence of human DNA. He also played a pioneering role in deciphering the secrets of antibody diversity. In 1992, Dr. Hood moved to the University of Washington to create the cross- disciplinary Department of Molecular Biotechnology, bringing together chemists, engineers, computer scientists, applied physicists and biologists. At the UW, he applied his laboratory's expertise in DNA sequencing to the analysis of human and mouse immune receptors and initiated studies in prostate cancer, autoimmunity, and hematopoietic stem cell development. In 2000, Dr. Hood founded the Institute for Systems Biology in Seattle, Washington to pioneer systems approaches to biology and medicine. He is President and Director of this organization and continues with his interest in biology, medicine, technology development, and computational biology. Dr. Hood has played a role in founding several biotechnology companies, including Amgen, Applied Biosystems, Systemix, Darwin, Rosetta, and MacroGenics. Numerous organizations have honored Dr. Hood with academic and scientific awards for his study of immune diversity, development of instruments to study biology and medicine, distinguished contributions to medical science, improvements to diagnostic methods, and efforts to open doors for new treatments and cures. For example, Dr. Hood was given the Lasker Award in 1987 for studies on the mechanism of immune diversity, the Kyoto Prize for Advanced Technology in 2002, and the Lemelson-MIT Prize for Invention and Innovation in 2003. Dr. Hood also holds honorary degrees from Montana State University, Mt. Sinai School of Medicine of the City University of New York, the University of British Columbia, the University of Southern California, Wesleyan University, Whitman College, Bates College, Johns Hopkins University, and The Pennsylvania State University.