Superior mesenteric artery (SMA) syndrome is one of the rare causes of small bowel obstruction. It develops following a marked decrease in the angle between SMA and the abdominal aorta due to weight loss, anatomical anomalies, or following surgeries. Nutcracker syndrome in the left renal vein may also occur following a decrease in the aortomesenteric angle. Though SMA syndrome and renal nutcracker syndrome share the same pathogenesis, concurrent development has rarely been reported. Herein, we report a 23-year-old healthy male diagnosed with SMA syndrome and renal nutcracker syndrome due to severe weight reduction. The patient visited our outpatient clinic presenting bilious vomiting and indigested vomitus for 3 consecutive days. He had lost 20 kg during military service. We suspected SMA syndrome based on abnormal air-shadow in the stomach and small bowel on abdominal X-ray; we confirmed compression of the third portion of the duodenum with upper gastrointestinal series and abdominal computed tomography (CT). Concurrently, renal nutcracker syndrome was also detected via abdominal CT and Doppler ultrasound. Considering bilious vomiting and no urinary symptoms, SMA syndrome was corrected by laparoscopic duodenojejunostomy, and close observation for the renal nutcracker syndrome was recommended. (Korean J Gastroenterol 2017;70:253-260)