A 56-year-old female presented to our hospital after being diagnosed with fecal occult blood and anemia duringa medical examination. Gastrointestinal endoscopy and abdominal contrast-enhanced CT revealed a 33 mm tumorlike lesion in the portion of the inferior duodenal angulus. Based on the histopathological findings of a biopsy, thediagnosis was duodenal gastrointestinal stromal tumor (GIST). Subsequently, the patient underwent wedge resection of the duodenum and duodenojejunostomy. The postoperative course was uneventful, and the patient wasdischarged on postoperative day 10. Surgical treatment of duodenal GIST aims to preserve as much function aspossible. Due to the anatomical complexity of the duodenum and the lower frequency of lymph node metastasis,the selection of the surgical technique and reconstruction method is important.