The 1992 International Yearbook of Nephrology is the 4th in a successful series of yearly books updating practising nephrologists and nephrologists-in-training on rapidly changing areas of nephrology. We were encouraged to proceed in our editorial venture by reviews of the previous issues which have appeared in various Nephrology Journals. These reviews have pointed to the successful use of the International Editorial Board, the broad range of topics of current interest which have been covered and the comprehensive and practical nature of the reviews. The principal aim of the Yearbook remains to provide reviews which are more current than those which appear in Nephrology textbooks and which can be in the hands of the readers a few months after the authors have completed the manuscripts. The appointed authors are always experts in the field, who are asked to give an objective review of the topic, up-dating the readers on the world-wide literature and providing them with a complete, accurate and up-ta-date list of important recent references. We have decided to maintain the successful format of the first three issues. Thus, the volume will continue to be divided into sections; each section will continue to have a different primary focus every year, depending upon what is of greatest interest at the time.