Summary.A short review is given of the results of recent investigations on the chemistry of the glycoproteins and especially of the present state of the question concerning the relations between carbohydrate and protein in these substances.Hyalomucoid, synovial mucin and submaxillary mucin were investigated with the aid of electrophoresis. In approximately neutral solutions the hyalomucoid and the synovial mucin proved each to contain two electrophoretically well‐defined components. In both cases the faster migrating component was found to consist of a pure polysaccharide acid (hyaluronic acid). The slower components were simple proteins. In native synovial fluid and native vitreous body fluid the hyaluronic acid in all probability is in no way combined with protein but exists solely in the form of salts of the inorganic bases present. The glycoproteins precipitated from neutral synovial fluid or vitreous body fluid on addition of acetic acid are to be regarded as purely artificial products.Neutral solutions of submaxillary mucin were, on electrophoresis, found to contain two distinct components, both proteins. The main component, which was the faster migrating one, amounted to about 90 % of the whole and was a glycoprotein containing 27 % carbohydrate. The other component probably ought to be regarded as a contaminant.Pure water extracts from cartilage contain chondroitin sulphuric acid exclusively in the free form. This confirms the old opinion of Mörner that the chondroitin sulphuric acid in the cartilage is partly present as alkali salt.A chemical classification of the glycoproteins is suggested.