Medical science is on the threshold of unparalleled progress as a result of the advent of genomics and related disciplines. Human genomics, the study of structure, function, and interactions of all genes in the human genome, promises to improve the diagnosis, treatment, and prevention of disease. This opportunity is the result of the recent completion of the Human Genome Project. It is anticipated that genomics will bring to physicians a powerful means to discover hereditary elements that interact with environmental factors leading to disease. However, the expected transformation toward genomics-based medicine will occur over decades. It will require efforts of many scientists and physicians to begin now to sort out the vast amounts of information in the human genome and translate it to meaningful applications in clinical practice. Meanwhile, practicing physicians and health professionals need to be trained in the principles, applications, and limitations of genomics and genomic medicine. Only then will we be in a position to benefit patients, which is the ultimate goal of accelerating scientific progress in medicine. In this inaugural article, we introduce and discuss concepts, facts, and methods of genomics and genetic epidemiology that will be drawn on in the forthcoming topics of the clinical genomics series.