The author's book, "Mikrochemie des Blutes," published in Vienna in 1935, was entirely sold out in two years. This new book has been produced from the experience gained from the earlier work. Additional methods largely developed by the author are now included, and with a change to a different language this is not in any sense a second edition. There are thirteen chapters and an appendix. The subjects covered are determinations of the general and physical qualities of blood; blood gas analysis; determinations of anions, kations, nonprotein nitrogen and its fractions, proteins and protein fractions, carbohydrates and their derivatives, ketobodies and polyvalent alcohols, fats and lipids, bile pigments and tests of hepatic function, enzymes, vitamins, sulfonamide drugs, para-aminobenzoic acid and thiocyanate. The appendix deals with solutions and apparatus. The brief chapter on vitamins deals with a method for determination of ascorbic acid, and the balance of the chapter is on