According to randomized prospective studies in humans, the Roux-en-Y gastric bypass provides more effective weight loss than vertical banded gastroplasty for morbid obesity. Ten pigs underwent laparoscopic Roux-en-Y gastric bypass to assess the feasibility of this procedure with conventional laparoscopic techniques and instruments. The procedure took an average of 4 h 20 min. Of the first five pigs killed immediately, four had correct anastomoses. Of the five remaining pigs with postoperative follow-up, three survived with an intact anastomosis and staple line at autopsy. Two died within 48 h, one from peritonitis (perforation of the small bowel), the other from unknown causes. A definite learning curve exists for this procedure primarily because of the extent of gastrointestinal reconstruction, but there is potential for it to be used in humans.