Aspegillosis in free-living birds can be occurred mostly under poor weather and climate. But, captive birds tend to be more susceptible to infection and diagnosis was made usually at post mortem. A two months old Whooper swan(Cygnus c. cygmus) dying suddenly was found in a zoo without prior clinical signs. At necropsy, numerous well- demarcated yellow to white firm nodules were scattered throughout the air sacs and the lungs. Microscopically, granuloma formations were observed in the lung and air sacs. The margin of granuloma was surrounded by connective tissue barrier and was infiltrated with lymphocytes, and also observed giant cell near the granuloma. By Periodic acid Schiff reaction, hyphae were detected in granuloma of lung and air sacs. This case was diagnosed as an invasive pulmonary aspergillosis caused by Aspergillus fumigatus infection in a Whooper swan at a zoo.