Few diseases have sprung into prominence more quickly than have the infectious hepatitides-infectious hepatitis and serum hepatitis. Both British and American troops suffered heavily during the World War years 1939-1945. During this period these diseases were assigned to the category of virus diseases, and extensive investigations were carried out in many laboratories in an attempt to isolate and define the properties of the etiological agents which actually remain undefined. To date, man is the only susceptible animal known to be infected by these agents. It would seem, nevertheless, that the whole range of animals has not been covered, and in an effort to plan future work in this field we have tried to list here all of the experimental efforts, which we have been able to find, either as recorded in the literature or as obtained from questionnaires. The data analyzed do not include all attempts to infect animals with the virus of infectious or serum hepatitis, but they probably include most of such attempts and have been collected with a view to providing a ready list of references so that workers may be able to see quickly what techniques have been used with certain animals, what the source of the infecting material has been, and what results have been obtained.