The authors report two cases of glucagonoma, a rare endocrine tumor of the pancreas, and describe the data currently found in literature. Glucagonoma is a single and usually large tumor, which develops in the alpha cells of the islets of Langerhans and evolves slowly. The combination of characteristic skin lesions, diabetes and weight loss should lead to searching for hyperglucagonemia and for the pancreatic tumor. The diagnosis is usually made rather late, average evolution is five years before diagnosis when it is detected. Imaging, in particular ultrasound and computed tomography (CT), proves to be necessary for the positive diagnosis of glucagonoma as it localizes the pancreatic mass and plays a role in local assessment, thus providing guidance for surgery. The role of imaging is also fundamental for the detection of metastases, which are the only sign of malignancy as no criterion of benignity is found for this tumor.