There has been a notable revival of interest in the chemistry of vitamins within the past few years. The recent work has led to the isolation of more or less completely crystalline compounds having the properties ascribed to vitamins A, B and D. The evidence now available appears to definitely establish the conclusion that vitamins are not to be classed with enzymes. The physiologically active crystalline products which now for the first time have been isolated make possible intensive studies of the constitution and chemical properties of the several vitamins. Although many years have been required to obtain these elusive compounds in the state of purity now reported, it is probable that their identification will be accomplished in a much shorter time. With the completion of this latter phase of the problem we may confidently look forward to the eventual synthesis of the vitamins and their extensive application to the nutritive needs of man.