The Human Genome Project is an international research effort the goal of which is to analyze the structure of human DNA and to determine the location of the estimated 100,000 human genes. Another component of the program is to analyze the DNA of a set of nonhuman model organisms to provide comparative information that is essential for understanding how the human genome functions. The project began formally in 1990. In this report, we summarize the rapid progress that has already been made; the impact that the resources already developed by the Human Genome Project have had on the ability of investigators to identify and isolate human genes, particularly those associated with disease; and the promise that the project offers for profoundly altering our approach to medical care, from one of treatment of advanced disease to prevention based on the identification of individual risk.