Background: Laparoscopic adjustable gastric banding (LAGB) is a safe and effective method for the treatment of obesity. The most common problem after LAGB has been the occurrence of prolapse (slippage) of the stomach through the band. It has been proposed that the pars flaccida (PF) pathway (dissection from the base of the right crus, along the left crus to the angle of His) is less likely to be associated with prolapse than the traditional perigastric (PG) pathway (dissection between the lesser curvature of stomach and lesser omentum, across the apex of the lesser sac, to the angle of His). We have tested this hypothesis using a randomized controlled trial format. Methods: We have performed a randomized controlled trial to compare the outcomes after LAGB using PF and PG pathways. 202 patients (mean age 40 years, mean weight 123 kg, mean BMI 45) were randomly allocated to the PF or PG pathway and followed for 2 years. Results: At 24 months, there have been 16 revisional procedures for prolapse, 4 in the PF group (all anterior prolapse) and 15 in the PG group (12 posterior and 3 anterior). This difference is significant (P<0.001). The mean % excess weight lost was 53% for the PF group and 46% for the PG group. There was equally significant improvements in the metabolic syndrome in both groups (59% preoperatively and 19% at 2 years). All 8 paired domain scores of the SF-36 measures of quality of life were improved significantly in both group (P<0.001). Conclusions: The PF pathway is as effective as the PG pathway in generating substantial weight loss, improved health and improved quality of life and is significantly less likely to be associated with prolapse (slippage). It is recommended as the primary dissection pathway.