This report deals with 20 patients studied angiographically with the clinical suspicion of islet-cell tumor whether or not such a tumor was eventually confirmed. Cases were also included in which angiography was performed for other reasons and arteriographic features simulating islet-cell tumor were noted. The angiographic features of functioning and nonfunctioning benign and malignant islet-cell tumors are described. Points of differential diagnosis of pancreatic and extrapancreatic lesions and structures are discussed. The inclusion of surgically verified cases, examples of false positive and false negative diagnosis as well as lesions simulating islet-cell tumors and other negative cases gives a more reliable picture of the values of angiography in the diagnosis of islet-cell tumor.