A major obstacle in the development of a specific diagnostic test for viral hepatitis has been the failure to adapt hepatitis viruses to animals, embryonated eggs, and cultures of a wide variety of tissues. This has forced reliance largely on human serum and feces as the only proven possible sources of antigen, the strength of which cannot be determined by any practical means now available. However, in spite of the obvious difficulties inherent in the problem, the search for an immunologic test has continued through the past two decades, resulting in the description of a considerable array of tests that utilize the techniques of complement fixation, precipitin reaction, collodion-particle agglutination, hemagglutination, and the intradermal injection of materials suspected of containing virus. A number of antigens, including serums and extracts of liver, spleen, and feces of patients in the acute phase of disease, extracts of normal tissues, and allantoic fluid obtained