Biliopancreatic diversion with a duodenal switch is a hybrid bariatric procedure combining restriction and malabsorption. This surgery was developed by combining Dr. Scopinaro's biliopancreatic diversion (BPD) and Dr. DeMeester's duodenal switch. The procedure is used for both primary and reoperative bariatric surgery. The study evaluated the first 440 patients who had no prior bariatric surgery. The average starting weight was 183 kg, with 41% of patients being super morbidly obese (BMI > 50). The average maximum weight loss was 80% of excess weight by 24 months post-operation, continuing at 70% for 8 years. Major complications occurred in nearly 9% of cases, with two perioperative deaths. All 36 type II diabetics discontinued medication. Seventeen revisions were performed to correct weight loss and low protein levels. No marginal ulcers, dumping syndrome, or foreign material were observed. The procedure preserves the pylorus and is functionally reversible. The operation significantly improved the lives of seriously obese patients with multiple comorbidities. All type II diabetics were essentially cured. The procedure was well-tolerated, with minimal weight regain. The first patient underwent the procedure after a failed transverse gastroplasty. He had a BMI of 50 and was free from obesity-related problems after 9.5 years. The first primary procedure was performed on a morbidly obese patient with a BMI of 46. He had an 88% excess weight loss. The first super morbidly obese patient had a BMI of 58.7 and a 78% excess weight loss. Both patients were doing well 9 years post-operation. The procedure is now the preferred method for treating morbid and super morbid obesity. The rationale for the duodenal switch is based on experimental studies showing that a small segment of proximal duodenum protects against marginal ulcers. The procedure involves a vertical gastrectomy to achieve gastric restriction. The study concludes that the biliopancreatic diversion with a duodenal switch is an effective and well-tolerated bariatric procedure. Keywords: Biliopancreatic bypass, duodenal switch procedure, malabsorption, morbid obesity, vertical gastrectomy, pylorus preservation.Biliopancreatic diversion with a duodenal switch is a hybrid bariatric procedure combining restriction and malabsorption. This surgery was developed by combining Dr. Scopinaro's biliopancreatic diversion (BPD) and Dr. DeMeester's duodenal switch. The procedure is used for both primary and reoperative bariatric surgery. The study evaluated the first 440 patients who had no prior bariatric surgery. The average starting weight was 183 kg, with 41% of patients being super morbidly obese (BMI > 50). The average maximum weight loss was 80% of excess weight by 24 months post-operation, continuing at 70% for 8 years. Major complications occurred in nearly 9% of cases, with two perioperative deaths. All 36 type II diabetics discontinued medication. Seventeen revisions were performed to correct weight loss and low protein levels. No marginal ulcers, dumping syndrome, or foreign material were observed. The procedure preserves the pylorus and is functionally reversible. The operation significantly improved the lives of seriously obese patients with multiple comorbidities. All type II diabetics were essentially cured. The procedure was well-tolerated, with minimal weight regain. The first patient underwent the procedure after a failed transverse gastroplasty. He had a BMI of 50 and was free from obesity-related problems after 9.5 years. The first primary procedure was performed on a morbidly obese patient with a BMI of 46. He had an 88% excess weight loss. The first super morbidly obese patient had a BMI of 58.7 and a 78% excess weight loss. Both patients were doing well 9 years post-operation. The procedure is now the preferred method for treating morbid and super morbid obesity. The rationale for the duodenal switch is based on experimental studies showing that a small segment of proximal duodenum protects against marginal ulcers. The procedure involves a vertical gastrectomy to achieve gastric restriction. The study concludes that the biliopancreatic diversion with a duodenal switch is an effective and well-tolerated bariatric procedure. Keywords: Biliopancreatic bypass, duodenal switch procedure, malabsorption, morbid obesity, vertical gastrectomy, pylorus preservation.