Two pheasants maintained in outdoor closed pen died within several days after having a history of depression. On necropsy, the spleens from both pheasants were enlarged about 3 times of their normal size and appeared mottled in color varying white to red. Histopathologically, there were diffuse severe follicular necrosis in the spleen and congestion and edema in the lung. Intranuclear basophilic inclusion bodies, which are strongly positive to group II avian adenovirus with immunohistochemistry, were noted in the spleen.