Population genetics is always accorded a place in the course on human genetics given in medical schools and it is usually given, as indeed it must be, a strongly mathematical treatment. The lack of reference to genetics in the journals reviewed is surely a reflection of a deficiency of convincing empirical evidence and a lack of practical experience with genetical characteristics and diseases. The geneticist will immediately see breathtaking opportunities in the new medicine. The ideas of prevention of disease and promotion of good health are implicit in the predictive function of genetics and have been explicitly stated, at least since the 1930s. It is always the hope of geneticists to put discoveries of the laboratory to use in the affairs of human beings. Some expressions of these hopes have appeared in the recent literature in the form of genetic engineering, reproductive manipulation, germinal selection, and the like.