After the great success of the fIrst issue of the series, the International Yearbook of Nephrology 1989, we were encouraged to proceed in our editorial venture to update nephrologists yearly, on all rapidly-changing areas of nephrology. Thus we have chosen new topics and appointed experts in the fIeld, asking them 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-to-date list of important, recent references. We have decided to maintain the successful format of the International Yearbook of Nephrology 1989. Thus each annual issue will be devided into sections; each section will have a different primary focus every year, depending upon what area is of greatest interest at the time. In other words, the Yearbook will remain different from the numerous books which appear every year covering all aspects of nephrology. In the Yearbooks you will fInd topics usually anavailable in nephrology textbooks. In this issue we have improved the printing quality of the book, with a more uniform format throughout the volume, despite the use of camera-ready manuscripts for direct photo-offset reproduction (a procedure mandatory for a rapid publication).