More than 50 years after Haas' first human dialysis, and second edition by incorporating chapters on its history 40 years after Kolfrs pioneering work, a book on the and on the practical aspects. present state of the art cannot be written by one person: The size of the book has almost doubled, partly by obviously it had to be a multi-authored volume. There- using more illustrations. The inclusion of a number of fore some overlap between chapters and even a few con- colour reproductions has been made possible by a sup- troversies between authors became unavoidable. porting grant * of the National Kidney Foundation of we deliberately avoided editorial streamlin- the Netherlands, which the editors gratefully acknow- However ing of manuscripts, leaving the authors' personal style ledge. We considered asking several authors to shorten their and personal opinions unaltered as much as possible. We resisted this as it would have delayed the This may make the book more vivid to read and may chapters. sometimes stimulate readers to study a subject in greater publishing date and would possibly have removed much detail from the literature. Additionally, both British and material besides being a painful task for our collea- American spellings have been kept because of the inter- gues.