This international conference addresses three new areas of pharmacogenetic and ecogenetic importance: 1) Foods and dietary constituents; 2) Genetic defenses against infections; and 3) Responses to drugs and environmental toxicants. The latter topic is subdivided in two parts which address New directions in the genetic and functional analysis of pharmacogenetic variants, and Considerations relevant to diagnostic pharmacogenetic testing: Optimizing drug discovery and drug therapy. The conference objective is a) to explore and document recent advances in pharmacogenetics and ecogenetics that will yield improved health care for large segments of human populations, and b) to facilitate the interaction of basic and clinical scientists engaged in the design and implementation of new technologies capable of screening for traits of pharmacogenetic and ecogenetic importance among subjects involved in clinical trials of new drugs and hospital patients. The speakers are of national and international caliber at the cutting edge of their topic. Some have established reputations in pharmacogenetics and ecogenetics, but we have also sought a balance that includes investigators from other fields. The roster of speakers includes a number of younger investigators who are contributing to the remarkable advances in research of potential pharmacogenetic and ecogenetic interest and to the utilization of the new knowledge in the discovery of new drugs and improved patient care.