An ulcerative skin disease has caused morbidity in both wild and cultured populations of American eel (Anguilla rostrata) in North Carolina, USA. Lesions appear to begin as localized, depigmented foci which spread to form large patches of necrotic skin. The depigmented patches detach at the dermo-epidermal junction, forming large ulcers that expose underlying muscle. The infection commonly affects the head, producing cranial swelling and corneal edema. A mild to severe, primarily mononuclear infiltrate is seen, most prominently in large ulcers. Many lesions had extensive collagen deposition, which contributed to the tissue swelling. Culture of skin lesions in various stages of development revealed the consistent presence of bacterial isolates that were biochemically and immunologically identified as Aeromonas salmonicida.