Fifteen SPF chickens were inoculated with an Australian strain of reticuloendotheliosis virus (REV) at 1 day of age and five uninoculated chickens were readily infected by horizontal spread from this group. Antibody detectable by the immunofluorescent antibody (IFA) test developed 3 to 6 weeks after infection, and usually persisted for 20–35 weeks, with maximum titres (40–1280) at 8 to 13 weeks. Agar gel precipitin (AGP) reactions developed more slowly and were variable in duration, the highest proportion of positive reactions being detectable 8 to 13 weeks after infection and persisting for 8 to 30 weeks. Infectious REV was readily detected in the plasma and serum of inoculated chickens 6 weeks after infection and a non-infectious REV antigenaemia usually persisted for at least a further 7 weeks, in the presence or absence of antibody. Development of a detectable REV viraemia was strongly associated with poor body development and premature mortality among the inoculated chickens. In two inoculated chickens which failed to develop detectable serological reactions, a REV viraemia occurred which persisted throughout life. At autopsy, REV was re-isolated from the kidneys of most of the inoculated chickens and from the reproductive and intestinal systems of two birds 22 and 56 weeks after infection. © 1979, Taylor & Francis Group, LLC. All rights reserved.