Abstract
12 marmosets of 3 different species died of hepatitis during a period of 5 months. The lesions closely resembled those of virus hepatitis in man but material from these animals and from in-contact marmosets failed to reveal the presence of hepatitis A. This together with certain aspects of the epidemiology of the disease suggests that the outbreak was not caused by a virus of human origin but possibly by a virus indigenous to the marmoset or tamarin.