This is a major initiative by the International Federation of Gynecology and Obstetrics (FIGO) and the Centre of Population and Family Health at Columbia University, New York, in collaboration with the World Health Ogranization, Geneva. It is designed to provide an up-to-date, comprehensive guide to all aspects of human reproduction. The three volumes have been written by an international team of contributors under the guidance of distinguished editors. Together they provide a systematic survey of the major principles of this subject. Special emphasis has been placed on the presentation of each volume which is interspersed with illustrations that enhance effective learning. There are over 550 illustrations throughout the text, and colour has been used wherever appropriate. Volume one provides a basis for the understanding of reproductive function and gives a description of the basic features of reproductive physiology. First, the anatomy and physiology of the hypothalamus and pituitary are explained. A review of the current knowledge and understanding of the regulation of gonadotropin secretion is presented and the various hormones and their mechanisms of action are discussed. Then the normal and abnormal mechanisms of sexual differentiation are described and the structure and functions of steroid hormones are presented, along with the analysis of the role of gonadotropins in sex steroid regulation. This provides a physiological and biochemical basis for the biological integration of the events described in the following three chapters. Chapter 3 discusses the physiology of reproduction in the female; puberty, ovulation, menstruation and sexual physiology are reviewed. The following chapter explains the development, structure and release of spermatozoa in the male and their passage and final maturation in the female reproductive tract. Chapter 5 returns to the germ cell and its development to a mature ovum. It then considers the physiological events that occur as fusion of the two gametes takes place and the newly created zygote is implanted in the endometrium. The final chapter gives an introduction to the subject of genetics. It is illustrated by reference to specific examples to show the way in which an understanding of genetic principles has led to the development of new approaches to the management and prevention of inherited disorders and to the counselling of affected families.