Superior mesenteric artery (SMA) syndrome is an uncommon cause of proximal intestinal obstruction, frequently occurring in patients who have had an important weight loss. The diagnosis can be difficult and usually is made by exclusion. The most characteristic symptoms are postprandial epigastric pain, fullness, voluminous vomiting and eructation. These symptoms are due to the compression of the third portion of the duodenum against the posterior structures by a narrow-angled SMA and surgical management is necessary. We report a case of SMA syndrome in a 23 year old patient, with a long history (since childhood) of voluminous vomiting, epigastric pain and an important weight loss. We performed small bowel enteroclysis, upper gastrointestinal series and endoscopy, biopsy of gastric and duodenal mucosa, abdominal computer tomography and ultrasonography to establish the diagnosis. Finally, the patient successfully underwent duodenojejunal anastomosis with a postoperative favourable outcome.