BACKGROUND Beside complications like band migration, pouch-enlargement, esophageal dilation, or port-site infections, laparoscopic adjustable gastric banding (LAGB) has shown poor long-term outcome in a growing number of patients, due to primary inadequate weight loss or secondary weight regain. The aim of this study was to assess the safety and efficacy of laparoscopic conversion to Roux-en-Y gastric bypass (RYGBP) in these two indications. METHODS A total of 25 patients, who underwent laparoscopic conversion to RYGBP due to inadequate weight loss (n = 10) or uncontrollable weight regain (n = 15) following LAGB, were included to this prospective study analyzing weight loss and postoperative complications. RESULTS All procedures were completed laparoscopically within a mean duration of 219 +/- 52 (135-375) min. Mean body weight was reduced from 131 +/- 22 kg (range 95-194) at time of the RYGBP to 113 +/- 25, 107 +/- 22, and 100 +/- 21 kg at 3, 6, and 12 months, respectively, which results in excess weight losses (EWL) of 28.3 +/- 9.9%, 40.5 +/- 12.3%, and 50.8 +/- 15.2%. No statistically significant differences were found comparing weight loss within these two groups. CONCLUSIONS RYGBP was able to achieve EWLs of 37.6 +/- 16.1%, 48.5 +/- 15.1%, and 56.9 +/- 15.0% at 3, 6, and 12 months following conversion, respectively, based on the body weight at LAGB.