In Vitro Fertilization, Embryo Transfer and Early Pregnancy is undoubtably the most exciting and onwardly progressing field in reproductive medicine today. It forms the major subject matter of this the second volume of the Proceedings and the first book of Related Communication papers given at the XI International Federation of Fertility Societies World Congress on Fertility and Sterility held in Dublin, Ireland from June 26th to July 1st 1983. The papers have been grouped into closely allied topics covering sequentially in three parts: Follicle and Ovum in the Human, Follicle and Ovum in the Animal Model, and Semen and Spermatozoa. Preceding a timely reminder on Ethical and Legal Aspects of IVF are some of the remarkable clinical results now been obtained throughout the world. The final section concerns various aspects of Pregnancy in Animals and Humans and is included in this volume because of its close relationship to the main subject matter. Related Communications sessions often produce the largest amounts of up-to-date information to be given on a particular subject during a Congress. IFFS Dublin '83 proved to be no exception. So although scientific and medical endeavour will ensure that knowledge and progress in the field will soom overtake many of the conclusions reached in these papers, nevertheless we hope you will agree in the merit of producing such a record of the state of the art at this time. Robert F. Harrison John Bonnar William Thompson Dublin 1983.