A captive mute swan (Cygnus olor) in the brooding period was found dead without any specific signs. On necropsy, the entire digestive tract was severely necrotized with loosely adherent pseudomembranes, and Clostridium perfringens (CP) colonies isolated from the intestinal contents were identified as CP type A by polymerase chain reaction. Microscopically, the intestine and the liver were necrotized and intralesional bacterial clusters were observed. In this case, there were no other mortalities, so the condition of a single bird, in particular, stress from incubation effort, could act as the predisposing factor for necrotic enteritis. In this study, we report a unique case of necrotic enteritis associated with incubation in a captive mute swan.