The plasma glycoproteins, mucoproteins, and mucopolysaccharides have been considered important in the pathogenesis or clinical evaluation of many diseases. The literature on this subject has become confused, however, because of inconsistencies in terminology and interpretations of findings. A brief review of this subject, in an attempt to clarify present knowledge of the field, seems indicated. The changes which occur in the plasma concentrations of the carbohydrates associated with the plasma proteins in various diseases and the present knowledge of the physiology of these compounds are of clinical interest. The relationship of some of these substances to carbohydrate compounds in the ground substance of connective tissue and to deposits found in several pathologic states also deserves review. Definition of the terms used is necessary at the outset; the recommendations suggested by Winzler1 have been used. Because of the variations in terminology in previous articles, it is necessary to consider the