Background and Study Aims: Premalignant duodenal polyps are considered to be rare. Recurrence after local excision is reported to be frequent, so many authors propose radical surgical treatment of these tumors. The aim of this study was to determine the long-term outcome after endoscopic resection of duodenal adenomas. Patients and Methods: Between January 1990 and April 2003 we retrospectively evaluated a group of patients who presented with nonampullary duodenal villous tumors but who did not have a polyposis syndrome. Results: Duodenal polyps were diagnosed in 21 patients during routine endoscopy during the study period. Of these, 18 patients (6 men, 12 women; median age 67, range 50 - 81), with a total of 20 duodenal adenomas, were enrolled into the study. The median size ± SD of the tumors was 27.5 ± 12 mm (range 8 - 50 mm). Of these 20 tumors, 18 adenomas were tubulovillous, one was tubulous and one was villous. Nineteen polyps were treated by snare excision and one adenoma was treated with argon plasma coagulation alone. Argon plasma coagulation was applied to polyps in six patients after snare excision during this initial treatment phase. The success rate for endoscopic adenoma removal after a 3-month interval was 55 %. After a median follow-up period of 71 months (range 22 - 151 months), 12 patients remained in remission. Local recurrences of the lesion occured in five patients (25 %) and these were re-treated. None of the patients developed carcinoma during the follow-up period. Conclusions: Endoscopic snare excision of duodenal adenomas is an effective mode of treatment but an endoscopic surveillance program is mandatory in order to detect and treat recurrence.