Avian Vacuolar Myelinopathy (AVM) is an emerging disease that is responsible for lesions of the CNS associated with morbidity and mortality of American coots (Fulica americana) and bald eagles (Haliaeetus leucocephalus) in the southeastern United States. The number of species and birds affected by AVM has been increasing since it was first described in DeGray Lake, AR in 1994. Since that time AVM has been found on eleven lakes in 5 states including Lake Surf, NC. Affected birds are incoordinated and ataxic. Histologic examination of the CNS shows a striking diffuse, spongiform degeneration of the white matter. This study investigates the occurrence and duration of the disease; climatic variables that may influence exposure; sources of potential food/water/substrate contamination; blood chemistry changes in affected birds and histologic examination of other verterbrates associated with the Lake Surf impoundment. Results narrowed the exposure window from mid-November through early January. Mallards showed lesions within 5 days and clinical signs within 7 days of exposure. A decrease in temperature was evident at the time of disease presence. There was also an associated decrease in water turbidity and an increase in pH. Food habit studies suggest that mallards and coots fed primarily on Hydrilla verticillata which was also the most abundant vegetation found in the lake. Histopathology results from five piscine species, nine muskrat (Ondatra zibethicus), a raccoon (Procyon lotor) and an opossum (Didelphis viriginiana) showed no AVM-like lesions. Blood chemistry data did not suggest signficant organ dysfunction.