BACKGROUND: Bariatric and metabolic surgery (BMS) is an established safe, effective, and durable treatment for obesity and its complications. However, there is still a paucity of evidence on surgery outcomes in patients suffering from extreme obesity. OBJECTIVES: This study aimed to evaluate outcomes of BMS in weight loss and the resolution of co-morbidities in patients with a body mass index (BMI) ≥70kg/m2. SETTING: National Health Service and private hospitals in the United Kingdom. METHODS: This cohort study analyzed prospectively collected records from the UK National Bariatric Surgery Registry of patients with a BMI ≥70 kg/m2 undergoing Roux-en-Y gastric bypass (RYGB), sleeve gastrectomy (SG), or adjustable gastric band (AGB) between January 2009 and June 2014. RESULTS: There were 230 patients (64% female) eligible for inclusion in the study: 22 underwent AGB; 102 underwent SG, and 106 underwent RYGB. Preoperative weight and BMI values were comparable (76 ± 7 kg/m2 for AGB; 75 ± 5 kg/m2 for SG; 74 ± 5 kg/m2 for RYGB). The median postoperative follow-up was 13 months for AGB (10-22 mo), 18 for SG (6-28 mo), and 15 for RYGB (6-24 mo). Patients undergoing RYGB and SG exhibited the greatest postoperative total body weight loss (35 ± 13% and 31 ± 15%, respectively; P = .14), which led to postoperative BMIs of 48 ± 10 kg/m2 and 51 ± 11 kg/m2, respectively (P = .14). All procedures conferred a reduction in the incidence of co-morbidities, including type 2 diabetes, and led to improved functional statuses. The overall complication rate was 7%, with 3 deaths (1%) within 30 days of surgery. CONCLUSION: This study found that primary BMS in patients with a BMI >70kg/m2 has an acceptable safety profile and is associated with good medium-term clinical outcomes. RYGB and SG are associated with better weight loss and great improvements in co-morbidities than AGB. Given the noninferiority of SG outcomes and SG's potential for further conversion to other BMS procedures if required, SG may be the best choice for primary BMS in patients with extreme obesity.