A review of all literature on jejunoileal bypass for obesity disclosed 282 deaths, corresponding to a mortality rate of 4.2 percent. This rate has been fairly constant through the last 8 years. The causes of death and the postoperative duration are quantified. Pulmonary embolism, mostly early, and liver disease, sometimes late, dominate among the numerous causes of death. Details are too scarcely reported to allow guidance to better results.