Duodenal neuroendocrine tumors (NETs) are rare neoplasms. In this study, the medical records of 14 patients with duodenal NETs diagnosed at Chonnam National University Hospital from July 2001 to August 2011 were reviewed and analyzed retrospectively. Four patients were diagnosed in the first 5 years, and 10 patients were diagnosed in the latter 5 years of the study. Ten of 12 patients (83.3%) who underwent endoscopic biopsy were confirmed to have NET before resection. Endoscopic resection was performed in 12 patients, surgical resection in one patient, and regular follow-up in one patient who refused resection. None of the patients showed recurrence or distant metastasis. Duodenal NETs are increasingly observed and are mostly detected during screening upper gastrointestinal endoscopy. Careful endoscopic examination and biopsy can improve the diagnostic yield of NETs. Most well-differentiated, nonfunctional duodenal NETs that are limited to the mucosa/submucosa can be treated effectively with endoscopic resection.