Thin smears of blood were examined from 157 wood ducks (Aix sponsa) trapped at Savannah National Wildlife Refuge (South Carolina, USA) and Harris Neck National Wildlife Refuge (Georgia, USA) during spring and summer, 1994 and 1995. Thirteen wood ducks (8%) were infected with blood parasites. Eleven of these birds were infected with Haemoproteus nettionis, seven with Leucocytozoon simondi, and five with unidentified microfilariae. Additionally, eight wood ducks (5%) were infected with Haemoproteus greineri. This is the first record of H. greineri in anatids trapped along the Atlantic Flyway south of Labrador and the first record of this species in wood ducks. To further characterize the distribution of H. greineri in the wood duck, blood smears were examined from hatching year ducks trapped at 10 different Atlantic flyway locations during spring and summer, 1980 to 1983. Haemoproteus greineri was found in wood ducks trapped in all 10 locations which extend from 46°N latitude in New Brunswick to 37°N latitude in Virginia. These findings indicate that H. greineri is not exclusively boreal in distribution, but also is found, at least in wood ducks, along much of the Atlantic Flyway.