Since its introduction in 1994, laparoscopic Roux-en-Y gastric bypass (LRYGB) has rapidly gained popularity for the treatment of morbid obesity. Historically, the operation is performed in a retrocolic fashion; however antecolic LRYGB has been advocated as a safe alternative. We reviewed our experience with both techniques. From January 2003 to November 2004, the new UCLA Laparoscopic Bariatric Surgery Program performed 341 LRYGBs. In March 2004, our program transitioned from a retrocolic to an antecolic approach for all gastric bypass procedures. Institutional review board approval was obtained, and the data for all patients was collected into a prospective database. The patient characteristics for the two groups were similar. The significant differences between the two groups were average body mass index and the percentage of patients with diabetes and sleep apnea. The complication profiles for the two groups were also similar. There were significant differences between the two groups in the reoperation rate, antecolic 2.0 per cent versus retrocolic 7.8 per cent, and length of stay, antecolic 2.57 versus retrocolic 2.89 days. There were no anastomotic leaks or deaths in either group. Antecolic LRYGB is safe and may be associated with fewer complications. Only long-term weight loss results and complication rates will provide a definitive answer.