Jejunoileal bypass for morbid obesity has been associated with a variety of long-term adverse sequelae, including excess diarrhea, electrolyte imbalance, kidney dysfunction, liver abnormalities, and polyarthropathy. Takedown of the bypass without providing a means of maintenance of weight reduction will lead to recurrence of morbid obesity. We studied 32 patients who underwent conversion of jejunoileal bypass to gastric bypass either in one procedure (27 patients) or more than one procedure (five patients). There were no operative deaths, but significant morbidity. Nevertheless, the conversion has maintained weight reduction and reversed the adverse effects of the small-bowel bypass. We concluded that conversion of the jejunoileal bypass to the gastric bypass, particularly with a Roux-en-Y anastomosis, in a single procedure is relatively safe, simple, and effective.