The aim of this study was to determine the safety and efficacy of laparoscopic duodenal switch (LDS) as a treatment option in a selected group of patients with morbid obesity. This retrospective analysis of a prospective database assessed the frequency of all complications and alterations in weight, body mass index (BMI), co-morbidity and quality of life. One hundred and twenty-one patients underwent LDS between April 2003 and March 2009. Median preoperative weight was 160 kg and median BMI 55 kg/m(2). All procedures were performed laparoscopically. The in-hospital mortality rate was zero. No ileoduodenal anastomotic stenosis was encountered. There were four clinical leaks (3ยท3 per cent) managed by laparoscopic drainage and placement of a feeding jejunostomy. Median percentage excess weight loss was 75 per cent at 12 months and 90 per cent at 24 months. Thirty-six of 40 diabetic patients had complete resolution of diabetes within 1 year. There were significant improvements in other obesity-related co-morbidity. Only a few patients developed postoperative protein deficiency, and fat-soluble vitamin deficiencies were easily managed with oral supplementation. The LDS procedure is a safe and effective treatment for morbid obesity and its associated co-morbidity in selected patients.