Introduction: The characteristics, prognostic factors, and management of duodenal neuroendocrine neoplasms (dNEN) are ill-defined, given their rarity. Whether nonsurgical management might be appropriate for patients with nonmetastatic dNEN and a good prognosis, as is the case for pancreatic NEN (pNEN), is unknown. We aimed to describe the management and prognosis of nonmetastatic dNEN patients. Methods: All consecutive patients with nonmetastatic dNEN managed between 1981 and 2018 in 2 expert centers were included. Recurrence-free survival (RFS) and factors associated with recurrence were estimated. Results: A total of 145 patients with dNEN were included. Twenty-eight patients with sporadic, nonfunctioning, small (median 7 mm) dNEN underwent endoscopic resection, with a 5-year RFS rate of 89.4%. Local recurrence occurred in 2 patients, who underwent surgery with no new events. The 5-year RFS rate was 87.9% in patients who underwent surgery. Upon univariate analysis, age, size, Ki67 index, and lymph node involvement (LN+) were significantly associated with worse RFS for all dNEN treated (endoscopy/surgery); multivariate analysis found that age, size, and LN+ were associated with worse RFS. Conclusion: Selected nonmetastatic dNEN had a favorable outcome, and a less invasive therapeutic strategy appeared more suitable than oncological surgery.