The glucagonoma syndrome is characterized by a necrolytic migratory erythematous rash, angular stomatitis, painful glossitis, a normochromic normocytic anemia, mild diabetes mellitus, weight loss, a tendency to thrombosis, and neuropsychiatric disturbances. The diagnosis is made by finding a high plasma glucagon concentration in the absence of any other cause, such as renal failure or severe stress. A pancreatic alpha-cell tumor can be identified and stained by immunocytochemistry with glucagon antibodies. Optimal treatment is surgical removal, but approximately 50 percent of the tumors have metastasized by the time of diagnosis. Since the tumor is slow-growing, remission can be obtained by hepatic artery embolization to shrink hepatic secondaries or by shrinkage, in about 10 percent of patients, with the combination chemotherapeutic regimen of 5-fluorouracil and streptozotocin. The rash frequently responds to administration of zinc, a high-protein diet, and control of the diabetes with insulin. Alongside the alpha cell in the islets of Langerhans is the D-cell, which produces somatostatin and may well act physiologically as a paracrine inhibitor of glucagon release. A newly developed, long-acting somatostatin analogue, SMS 201-995, which the patient can self-administer as a subcutaneous injection, has proven effective in suppressing glucagon secretion from glucagonomas and, in some cases, causing remission of clinical symptoms.