The efficacy of three gastric restriction operations were compared in a prospective randomized study of 310 morbidly obese subjects. The median patient age was 34 years (range, 18 to 62 years). They were predominantly female (13:1) and had a median pre-operative weight that was 198% of their ideal weight (range, 160% to 318%). There was an equitable dispersion of perceived risk factors between the groups under study and there were no deaths during the perioperative period. Compliance with follow-up at 3 years was 91%. When success was defined as a loss of more than 50% of excess weight or a current pregnancy, the success rates at 3 years were 17% for gastrogastrostomy, 48% for vertical gastroplasty, and 67% for Roux-en-Y gastric bypass (p less than 0.001). Although the gastric bypass operation took longer to perform, there were similar outcome patterns for the three groups during the postoperative period. We conclude that the Roux-en-Y gastric bypass is the preferred procedure for the surgical treatment of morbid obesity.