Four 23-day-old cockatiels (Nimphicus hollandicus) were inoculated with a homogenate of feathers and skin infected with the psittacine beak and feather disease virus (PBFDV;0.5ml/bird). Another bird served as control. The inoculated birds molted and had dystrophic feathers in the third post-inoculation (pi) week. Necropsy revealed that thymuses were slightly atrophic in the first week pi and severely atrophic in the fourth week pi. In histological changes, mild heterophil infiltration was observed in the feather pulp in the first week pi. Severe macrophage infiltration with occasional basophilic intracytoplasmic inclusion bodies occurred in the fourth week pi. Eosinophilic intranuclear inclusion bodies were observed in feather epithelial cells. In the inoculated birds, the marked starry-sky phenomenon was observed in the thymus and bursa of Fabricius in the first week pi and cortical atrophy in the fourth week pi. In the first and fourth week pi, the PCR method revealed PBFDV-specific DNA products in feathers from all the inoculated birds but not in feathers from the control.