Laparoscopic sleeve gastrectomy has gained popularity as a weight loss surgical option for morbidly obese patients. Although initial studies have shown weight loss and comorbidity resolution comparable to those after laparoscopic Roux-en-Y gastric bypass (RYGB), many of these studies are limited by the small patient size. Thus, the purpose of this study was to compare the outcomes of laparoscopic sleeve gastrectomy and laparoscopic RYGB. A retrospective chart review of all morbidly obese patients who underwent laparoscopic RYGB or sleeve gastrectomy between 2007 and 2009 at an HMO hospital was conducted. Data points collected included age, gender, completion of a preoperative weight loss program, initial body mass index (BMI), pre- and postoperative weights, and presence of diabetes mellitus (DM), hypertension (HTN), osteoarthritis, obstructive sleep apnea, and gastroesophageal reflux disease (GERD). Outcomes measures included excess weight loss, resolution of comorbidities, postoperative complications, and mortality. A total of 345 laparoscopic RYGBs and 192 sleeve gastrectomies were performed. On average, the patients who received RYGB were younger (46 vs 48 years, P = 0.05) and had higher BMI (47 vs 43 kg/m(2), P < 0.0001). There was a higher incidence of DM in the RYGB group (32 vs 22%, P = 0.01), whereas the incidences of HTN and GERD were similar in both surgical groups. Ninety-three per cent of the patients who underwent RYGB and 90 per cent of the patients who underwent sleeve gastrectomy completed a preoperative weight loss program. The median length of hospital stay for both groups was 3 days. The complication rate in both groups was 9 per cent. The incidence of gastric leak was 1 per cent in both groups. There was only one mortality, which occurred in the RYGB group. The postoperative resolution of DM was comparable in both groups. The RYGB group had greater resolution of HTN (48 vs 34%, P = 0.03) and GERD (73 vs 34%, P < 0.0001). At 12 months, sleeve gastrectomy achieved superior excess weight loss compared with RYGB (72 vs 61%, P = 0.0015). After adjusting for age and BMI, the excess weight loss for RYGB and sleeve gastrectomy was similar at 12 months (t parameter estimate -0.06, P = 0.08). Laparoscopic RYGB and sleeve gastrectomy had comparable postoperative morbidity and mortality rates. At 1 year, sleeve gastrectomy achieved only slightly greater weight loss. The two operations are both legitimate standalone bariatric procedures and their applications need to be based on individual patient characteristics and needs.