['This report examines the < or =30-day postoperative mortality and morbidity in our first 190 duodenal switch (DS) patients.', 'DS is the most weight loss effective and the most difficult to perform bariatric procedure. Indeed, certain surgeons have advocated a 2-stage approach to minimize complications, especially in the super obese (body mass index [BMI] > or =50 kg/m(2)).', 'DS procedures were performed (n = 190) by either open (n = 168) or laparoscopic/robotic surgery in an academic setting: common channel 75 to 125 cm, sleeve gastrectomy (approximately 100 mL gastric pouch), closed duodenal stump, end-to-side duodenoileostomy hand-sewn in 2 layers, with most staple lines oversewn, and all mesentery defects closed.', 'For the 190 patients, 149 were female (78%) and the mean age was 43 years (range, 16-71). Mean preoperative weight 151.4 kg (range, 74.1-332.7); mean preoperative BMI 53.4 kg/m(2) (range, 32-107), with 100 (52.6%) of the patients super obese (BMI > or =50 kg/m(2)). Seventy-four patients had concurrent procedures, eg, cholecystectomy (n = 22), ventral or umbilical hernia repair (n = 19), and hiatus hernia repair (n = 10). Mean operating room time was 337 minutes (range, 127-771); mean hospitalization time was 6 days (range, 2-38). There were no deaths. Serious < or =30-day complications (n = 18 in 14 patients) consisted of 2 leaks (1.0%), which responded to drainage, and intra-abdominal bleeding (n = 3), splenectomy (n = 1), acute pancreatitis (n = 2), gastric outlet obstruction (n = 1), acute renal failure (n = 2), pneumonia (n = 2), respiratory failure (n = 3), acute myocardial infarction (n = 1), and duodenoileostomy stricture requiring endoscopic dilation (n = 1). The serious complication rate in patients with a BMI <50 kg/m(2) was 6.7% (6 of 90) and 12% (12 of 100) with a BMI > or =50 kg/m(2) (NS). Surgical site infections occurred in 7 patients with a BMI <50 kg/m(2) and in 12 with a BMI > or =50 kg/m(2) (NS). Overall complication rate in patients with a BMI <50 kg/m(2) was 14.4% (13 of 90) and 24% (24 of 100) with a BMI > or =50 kg/m(2) (NS).'] Are duodenal switch operative mortality and morbidity impacted by body mass index?