Psittacine beak and feather disease (PBFD) virus, was purified from diseased tissues of a lesser sulphur-crested cockatoo (Cacatua sulphurea), a black palm cockatoo (Probosiger aterrimus), a red-lored Amazon parrot (Amazona autumnalis), and a peach-faced lovebird (Agapornis roseicollis). The histopathology of diseased feathers and follicular epithelium from the different species was compared; basophilic intranuclear inclusion bodies were identified in the follicular epithelium and intracytoplasmic globular inclusions were observed within macrophages located in the feather pulp from the four species. Psittacine beak and feather disease virus antigen was specifically detected by colloidal gold immunoelectron microscopy. The different preparations of purified virions displayed an icosahedral symmetry, were non-enveloped, and had a mean diameter that varied from 12 to 15 nm when negatively stained. Two major viral-associated proteins with approximate molecular weights of 26 and 23 kilodaltons (kd) were consistently demonstrated from the four viral preparations. Purified virions from the four genera were antigenically related. These findings suggest that the PBFD virus purified from numerous genera of diseased birds is similar based on ultrastructural characteristics, protein composition and antigenic reactivity.