Gastrointestinal stromal tumors are the mostly seen mesenchymal tumors of the gastrointestinal system. This rare tumor in duodenum is seen 5%. The diagnosis and treatment is hard because of its rarity and location. Case: A 63-year-old man with a solid mass at the third part of the duodenum, and local segmental resection of the tumor was performed. The histopathology was reported as gastrointestinal stromal tumor of the duodenum with negative surgical margins. Discussion: Gastrointestinal stromal tumors at the duodenum are seen rarely. They can be asymptomatic or may involve symptoms of upper GI bleeding and abdominal pain at presentation. Because of the misleading clinical presentation the differential diagnosis may be difficult. Tumors less than 2 cm can be followed by endoscopic ultrasound. Local segmental resection with 1cm clear margin is the treatment choice.