BACKGROUND Severe or extreme obesity in children and adolescents is a progressive damaging disease, increasingly requiring surgical treatment. Timing and choice of operation are controversial. METHOD In the last 16 years, we performed open biliopancreatic diversion with duodenal switch (DS) in 13 adolescents aged 15-17 years, who have been followed up for 2-16 years (mean, 10.6 years); three with Prader-Willi syndrome (PWS) are presented separately. RESULTS Among the ten non-PWS children (7 girls), no deaths or perioperative complications were reported, mean body mass index (BMI) decreased from 55.9 ± 14.0 to 28.8 ± 3.7 kg/m(2) (% excess weight loss (EWL) = 82.1 ± 10.5%), and none have regained weight. All comorbidities were cured except asthma, which improved in one patient. There were two reoperations: one for intestinal obstruction and one for post-anastomotic ulcer. Glucose and lipid metabolism improved, while vitamin and mineral deficiencies were mild and rare. Five of the seven girls gave birth to 11 children, aged 2-12 years, two of whom are overweight but not severely obese. Neurodevelopment is age-appropriate in all 11 individuals. PWS children, aged 15-16 years, had postoperative respiratory and infectious complications necessitating hospitalizations of 13-22 days (versus 5.1 ± 1.2 days in non-PWS). Weight loss and comorbidity improvement lasted approximately 5 years, providing improved quality of life for patient and family. One PWS patient died from complications after reoperation for weight regain after 4 years. One was reoperated after 6 years and the third is considering reoperation 14 years after primary DS. CONCLUSION The beneficial effects of DS in adolescents exceed the risks, even in the presence of PWS.