SINCE LOW-FAT DIETS are often effective in reducing serum cholesterol concentration, the possibility was suggested that a decreased absorptive area in the small intestine might result in low fat absorption and decrease in serum cholesterol and lipoprotein concentrations. Dr. Howard Payne, Los Angeles County Hospital, had found that short-circuiting the small intestine of excessively obese subjects resulted in weight reduction with ultimate stabilization of weight at normal levels in some cases. Our study was carried out on 2 extremely obese women. In one, the jejunum was divided 20 in. below the duodenum and anastomosed to the transverse colon. In the other, the jejunum, after division, was anastomosed to the cecum instead of the transverse colon. Studies before and for 2 to 3 years after surgery show that the serum cholesterol and β-lipoprotein concentrations were significantly decreased after operation. Body weight fell from 237 lb. (107.7 kg.) to 145 lb. (65.9