['Although biliopancreatic diversion with duodenal switch (BPD-DS) is not the most performed procedure, Roux-en-Y gastric bypass (RYGB) is challenged by weight regain and insufficient weight loss, especially in patients with a body mass index >50 kg/m(2). The aim of our retrospective study was to compare the weight loss after 2 types of primary bariatric surgery. A total of 83 BPD-DS and 97 RYGB procedures were performed from March 2002 to October 2009 for an initial mean body mass index of 55 kg/m(2).', 'All RYGB patients underwent surgery at a private practice hospital and BPD-DS patients underwent surgery at a university hospital before February 2007 and at the same private hospital thereafter. The patients were seen in follow-up every 4 months the first year, every 6 months the second, and yearly thereafter. The maximum weight loss was assessed, as well as the weight regain beyond the first postoperative year. Weight loss success was defined as a percentage of excess weight loss (%EWL) of ≥50%.', 'The patients did not differ by age, gender, or length of follow-up (mean 46 mo, range .5-102 for RYGB and 44.3 mo, range 9-111 for BPD-DS). Of the patients, 17 RYGB and 7 BPD-DS patients were lost to follow-up within 3 years postoperatively. At 3 years of follow-up, the mean %EWL was 63.7% ± 17.0% after RYGB and 84.0% ± 14.5% after BPD-DS (P < .0001). Weight loss success was achieved by 83.5% of the RYGB and 98.7% of the BPD-DS patients (P = .0005).'] Is weight loss more sustained after biliopancreatic diversion with duodenal switch than Roux-en-Y gastric bypass in superobese patients?