- This study was undertaken in order to evaluate the implications of substituting a failed jejunoileal bypass with a gastric bypass, another bariatric procedure. During the same operation, the jejunoileal bypass is taken down and a Roux-en-Y gastric bypass created. All 12 patients who underwent the procedure and who form the basis for this study survived. In comparison with patients who underwent gastric bypass alone during the same period, peri- and postoperative morbidity did not increase. Following this operation blood glucose levels and arterial blood pressure decreased as the patients with the failed jejunoileal bypass lost weight. Serum cholesterol and triglyceride levels, which are known to decrease significantly after jejunoileal bypass, slightly increased but always remained within normal range after substitution by the gastric bypass. All patients who underwent the combined operation showed a dramatic improvement in life quality. We conclude that the simultaneous performance of these two procedures is a preferable alternative to the take-down alone of the original unsuccessful procedure.