The Symposium on "Protein Metabolism: Infiuence of Growth Hormone, Anabolie Steroids, and Nutrition in Health and Disease" is the fourth in the series of International Symposia sponsored by CIBA Limited, Basle. As in the case of the previous conferences, it was planned and organised with the help of experts in the field concerned. Special thanks are due to Prof. A. QuERIDO and Dr. A. A. H. KAssENAAR who, once the idea of the Symposium had been conceived in the course of joint discussions, embarked upon the project with enthusiasm and inspiration, although they must have known full weil what a great deal of time and trouble the organisation of such a meeting would inevitably cost them. For their untiring efforts, for the judicious manner in which they contrived to select precisely those subjects on which interest is chiefiy centred today, and-last but not least-for their success in finding competent specialists to participate in the proceedings, we wish to assure them of our sincere gratitude. To all the members of the Department of Clinical Endocrinology and Diseases of Metabolism, at the University Hospital in Leyden, who helped in preparing the meeting, we would likewise extend a warm vote of thanks. The fact that the present volume, featuring the papers and discussions of the Symposium, has been published only a few months after the event, was made possible thanks to the co operative help of all who participated.