A swift and aggressive diagnostic and therapeutic approach is advisable when managing submucosal or polypoid lesions in the duodenum, since it is not possible to distinguish small, benign, and unremarkable duodenal growths macroscopically from malignant tumors such as carcinoids. This paper presents a systematic review of the published literature listed in Medline, focusing on the results after endoscopic treatment of duodenal carcinoids during the last 15 years; on the biological behavior of duodenal carcinoids; and on the endoscopic appearance of duodenal carcinoids. Endoscopic ultrasonography (EUS) is extremely useful in the diagnostic and preoperative work-up. The results indicate that endoscopic removal of duodenal carcinoids smaller than 1 cm that are located outside the periampullary region, with no EUS signs of invasion of the muscularis propria, is a safe, patient-friendly, adequate, and effective treatment.