In recent years, interest in the normal chemistry and physiology of the blood proteins, that is, albumin and the globulins, has increased tremendously as newer more refined techniques of study of the physicochemical nature of these important body constituents have become available. Concurrently, much interest has been aroused in the pathologic physiology of proteins. Some disease states, such as multiple myeloma, are primarily characterized by the presence of abnormal proteins in the serum. In other diseases, e.g., lupus erythematosus and the collagen group, rheumatoid arthritis, lymphosarcoma, and Boeck's sarcoid, abnormal proteins are being searched for and found as manifestations or causes of these various disease entities. Waldenström's macroglobulinemia is a recently recognized disease characterized primarily by the presence of abnormal proteins in the serum. Three patients with this disease will be presented, each of whom showed major disorders of the retinal veins presumably as a direct consequence of the abnormal