Haemoproteus infection was confirmed in white Pekin ducks (Anas platyrhynchos domesticus) following placement in a pond where severe mortality from a respiratory condition apparently caused by schizonts of Haemoproteus had occurred in muscovy ducks (Cairina moschata). Blood from one infected white Pekin duck was experimentally inoculated into five muscovy ducks; two of the five developed large numbers of schizonts in the endothelial cells and died. Illness did not occur in the white Pekin ducks.