Introduction: Adenocarcinoma of the third part of the duodenum is a rare type of tumor that has challenges in its diagnosis and management. Segmental resection with pancreatic sparing is a safe and accepted choice for the surgical intervention of this type of cancer. Case Presentation: A 33-year-old male presented with a 3-week history of symptoms of gastric outlet obstruction with anemia and weight loss. Upon investigating the patient with computed tomography and esophagogastroduodenoscopy, he was found to have an adenocarcinoma that involved the third part of the duodenum. The patient underwent segmental resection of the third and fourth part of the duodenum with pancreatic sparing. He had a smooth postoperative course. The pathological evaluation shows a 3 cm moderately differentiated adenocarcinoma with free margins. Six out of thirteen lymph nodes were having metastasis. The patient developed a soft tissue recurrence 18 months after the operation. Takeaway Lessons: Adenocarcinoma of the third part of the duodenum should be kept in mind in any patient presented with symptoms of gastric outlet obstruction. It can be managed safely with segmental resection avoiding the morbidity of resection of the pancreas. Keywords: Adenocarcinoma of the small bowel, third part of the duodenum, segmental resection Note: This case report is prepared using the CARE Checklist (2013) of information to include when writing a case report (https://www.care-statement.org). The CARE guidelines for case reports help reduce bias, increase transparency, and provide early signals of what works, for which patients, and under which circumstance.