A biliopancreatic bypass operation has been used to treat obese patients since June 1978, and 10 women have been followed-up for over a year. Biliopancreatic shunts reduce food absorption by eliminating enzymatic and biliary secretion activity in the intestinal lumen. Bodyweight loss was satisfactory, was proportional to excess weight, and was evaluated as being a mean of 33.1 kg. The constant and sometimes dramatic diarrhea provoked by conventional jejuno-ileal bypass operations was not observed. Hepatic steatosis, frequently present to varying degrees, was never made worse : in one case it even disappeared completely, while in another case biological tests conducted one year after operation showed considerable regression. Neither severe complications nor mortality were reported in this series.