Abstract IN THIS review an attempt is made to coordinate the nomenclature used by the various investigators in designating the several components of the vitamin B-G complex and to present the more recent findings regarding these components, especially those findings that concern the interrelationships between the components and the oxidative enzymes. With great rapidity, many laboratories have contributed to the accumulation of knowledge concerning the vitamin B-G complex. Some of the more outstanding contributions to the progress of the study of the vitamins of the B-G complex are listed in Table 1. These contributions were, for the most part, the outgrowth of a large number of isolated observations made in many different laboratories by research workers who were studying the vitamin requirements of different species of animals and investigating the distribution and the chemical and physical properties of the components of the B-G complex. Not only were the vitamin concentrates prepared . . .