This report describes inclusion body hepatitis in a 12-week-old leghorn-type cockerel. The cockerel had come from a specific-pathogen-free flock and was reared in a positive-pressure isolator until 6 weeks old. Grossly, the cockerel was jaundiced, and the liver was swollen and had small white foci throughout. Histologically, there were foci of hepatic necrosis and basophilic inclusion bodies in the nuclei of numerous hepatocytes. A fowl adenovirus, isolated from the liver, was found to belong to serotype 2/12. The bursa of Fabricius had some degenerative changes, but these were not consistent with infectious bursal disease, nor was there evidence of seroconversion to infectious bursal disease virus in the remaining chickens.