This symposium was held at the University of Wisconsin and sponsored by the Wisconsin Alumni Research Foundation. Included with the papers are brief abstracts of several round table discussions held during the conference. A wide variety of the many aspects of steroid hormones are covered. Appropriately, the first two presentations deal with the historical development of knowledge of the chemistry and physiology of the steroids. Against this setting, present day concepts of the biosynthesis of steroids and their metabolism in humans are discussed. Specific aspects of steroid metabolism are discussed, with particular emphasis on protein metabolism. Two papers summarize briefly current information on the tumorigenic and antitumorigenic effects of these hormones. Much attention is paid to practical use of steroid hormones in promotion of growth and fattening of animals and the effects of these hormones on pregnancy and lactation. These papers will be of interest to veterinarians and animal breeders.