INCREASING awareness of human infectious hepatitis and the common occurrence of infectious canine hepatitis in the United States have precipitated queries about the possible transmission of the canine disease to man, particularly when illness occurs simultaneously or has similar manifestations in a pet and in a family member. Perhaps the name "hepatitis" in the designation of the canine disease is unfortunate since it suggests a relationship to human hepatitis. Actually the virus infects the reticuloendothelial system in general, and hepatitis is not a primary lesion. Frequently hepatitis is not manifested clinically, but lymphadenopathy, tonsillitis, and endothelial invasion are more constant lesions. Since infectious canine hepatitis virus was first described by Rubarth in 1947 (1), a great deal has been learned about the disease in its natural host and about its causal agent. Although the virus was known to cause an encephalitis in the fox, there was no suggestion in the early literature that man was also a host. However, at least one later study suggested that canine hepatitis virus can cause hepatic complications in man (2). This report reviews the literature on infectious canine hepatitis virus to help clarify its position in relation to human disease.