An adenovirus was isolated from the pancreas, kidney, and lung of a dead 4-month-old ostrich (Struthio camelus). Experimental infection of week-old guinea fowl (Numida meleagris) was carried out in order to study transmission. Of the infected keets, six out of 15 died; these exhibited pancreatitis, presence of a hemorrhagic liquid in the abdominal cavity, kidney degeneration, and pulmonary lesions. The remaining birds, euthanatized on day 21 postinoculation, showed chronic pancreatitis. The virus was reisolated from the pancreas, lung, and kidney of the infected keets.