A series of 18 patients underwent surgery for upper abdominal symptoms and signs of superior mesenteric artery syndrome (SMAS). The diagnosis was made by simultaneous arteriography and barium meal. Findings at operation confirmed SMAS in every patient, and a duodenojejunostomy was performed. Duodenal and jejunal wall biopsy from 13 patients revealed normal myenteric and submucous plexuses. A follow-up study of 16 patients was performed after 7 years. At follow-up, the weight loss seen preoperatively had been corrected. However, symptoms were essentially similar to those found at the original examination. Only the frequency of the most distressing symptom, vomiting, was significantly decreased (p less than 0.05). The most striking features in the production of the "pincher mechanism" of the duodenum were found to be a short aortomesenteric distance together with sagittal parallelism between aorta and superior mesenteric artery. In conclusion, we recommend a conservative attitude in the treatment of SMAS. Surgical treatment with duodenojejunostomy may be indicated only if vomiting is a predominant symptom and proper conservative treatment has failed.