Carcinoids of the stomach, duodenum, and pancreas are represented by a variety of tumors with variable histologic and clinical features. Multicentric gastric carcinoids and concomitant nonantral argyrophilic hyperplasia are common in chronic atrophic gastritis, more rarely due to a multiple endocrine neoplasia (MEN)-related Zollinger-Ellison syndrome (ZES). These tumors are infrequently associated with metastases and may generally be dealt with by repeated endoscopic fulguration. Sporadic carcinoids tend to be larger, invasive, and more often metastatic, especially in the presence of atypical histology. Small tumors may be removed by endoscopy, but larger lesions need to be surgically excised. In association with metastases a histamine-related atypical carcinoid syndrome may evolve and require treatment with a somatostatin analog. Poorly differentiated neuroendocrine carcinomas of the stomach constitute markedly aggressive tumors that rarely are suitable for radical surgery. Gastrinomas are the most prevalent duodenal carcinoids and a common cause of ZES especially in MEN-I. Despite a marked tendency for regional lymph node dissemination, liver metastases occur late and duodenal gastrinomas are often excisable, thereby offering favorable odds for cure in ZES. Unusual somatostatin-rich carcinoids in the ampulla of Vater relate to von Recklinghausen's disease and may be the cause of obstructive jaundice; depending on their size, these tumors may be removed by local excision or pancreaticoduodenectomy. Gangliocytic paragangliomas are unusual, generally benign lesions of the duodenum. Rare pancreatic tumors with serotonin immunoreactivity may be classified as carcinoids and constitute an unusual cause of the carcinoid syndrome.