A comparative study has been made of three methods for the operative treatment of obesity. Of my own cases, 235 underwent a jejunoiliac bypass procedure, and the results have been analyzed: operative lethality 2.1%; postoperative complications 21%. Of the patients whose residual ileum was quite short (about 45 cm), about 70% reached their ideal weight. Metabolic late complications were considerable (e.g., liver damage in 15%, electrolyte deficit in 12%, and arthritis in 10%). In the late observation time of 14 years, 14 patients died, 10 of them as a result of the operation. Three different stomach-bypass procedures are described. The collective statistics compiled on 1585 patients indicated 1.6% postoperative lethality and 22% postoperative complications. Of the total patients. 90% were very satisfied with the procedure and in only 5% was a weight gain recorded after 5 years. The latest procedure is gastroplasty according to the Gomez method: the first 200 cases show 0.5% postoperative lethality and postoperative complications in 18.5%. Although this procedure is technically simple, the late observation time is not yet adequate for a definitive comparison.