The experiments of Havens, Ward, Drill and Paul, a Neefe and his associates4, 5,~,~ and:Paul, Havens, Sabin and Philip 9 on human volunteers make the virus etiology of infectious hepatitis at the least highly probable. The virus seems to be present in the blood, the feces and perhaps in the urine and the throat washings. As the human experiment has its limitations, details of several aspects of the disease will remain unknown unless a susceptible animal has been found.