Diseases occurring in captive waterfowl at an Ontario park maintained for research and public education were studied over a three-year period, 1967–1970. Organic diseases, probably causally associated with stresses of captivity, were the most serious mortality factors. These diseases were amyloidosis, myocardial infarction, and gout. With the exception of aspergillosis and one serious outbreak of Pasteurella anatipestifer infection, infectious diseases were of secondary importance.