A nine-month-old male ostrich (Struthio camelus) exhibited loss of appetite and dyspnea for 10 days, followed by emaciation and death. Grossly, multiple white nodules measuring 1-3 mm in diameter were observed in the surface of and inside of the lung and in the mucosa of the air sac. Microscopically, the granuloma formations were observed in the lung and air sac. The core of granuloma consisted mainly of macrophages and fibroblasts. The thin layer comprising the giant cells and macrophages surrounded the granuloma. By Periodic acid Schiff reaction, mycelia were detected especially in the core of granuloma. From the present results, the causative agent inducing the death of an ostrich was thought to be Aspergillus sp. This is the first report of the occurrence of acute Aspergillus pneumonia (brooder pneumonia) in an adult male ostrich in Korea.