It was the year of 1969 when this monograph was originally published in Japanese by Professor TADASHI KAWAI, titled as "The Plasma Proteins, Their Fundamental and Clinical Aspects." After I read through the Japanese edition, I was impressed by its rather complete coverage of the subjects and their detailed descriptions. I have felt that this excellent monograph should be distributed not only among our Japanese scien­ tists but also among many other colleagues throughout the world. I am happy, the­ refore, to know that the English edition of his monograph, partly revised, is ready to be published at this time. Professor KAWAI received his postgraduate medical training in U.S.A. for seven years, and was certified by the American Board of Pathology in both Anatomical and Clinical Pathology in Fall, 1962. Thus, I believe, he is the most suitable fellow for publishing the English edition of this kind.