The case of a 57-year-old diabetic man with necrolytic migratory erythema in the absence of glucagonoma is reported. The clinical and pathologic features of his dermatitis and subsequent clinical course are compared with those of canine superficial necrolytic dermatitis, an unusual cutaneous necrotizing eruption of dogs that is identical histologically to necrolytic migratory erythema. In addition to a necrolytic dermatitis, both our patient and most dogs with superficial necrolytic dermatitis have diabetes mellitus and hepatic failure in the absence of glucagonoma. Thus hyperglucagonemia most likely is not a factor in the origin of the necrotizing dermatitis in this patient or in dogs. The role of hepatocellular dysfunction in the pathogenesis of necrolytic migratory erythema and superficial necrolytic dermatitis is considered.