Bacterial translocation from the gut is implicated in the pathophysiology of complications associated with obstructive jaundice. Absence of intraluminal bile salts and their antiendotoxic effects may result in overgrowth of bacteria, promoting bacterial translocation. The large bowel is the largest source of gram negative bacteria but the small bowel is more permeable. This study investigated the effect of obstructive jaundice on bacterial translocation and on the indigenous luminal microflora at 3 sites in the gastrointestinal tract. Significant bacterial translocation was demonstrated following 7 d of bile duct ligation compared with control or sham operated groups. A qualitative disturbance of the caecal indigenous microflora was demonstrated in jaundiced rats. There was no 'site-to-site' variation in the indigenous microflora at the 3 intestinal sites studied. We conclude that experimental obstructive jaundice for 1 wk promotes bacterial translocation without significant quantitative disturbance of the intestinal microflora in the small intestinal or caecum.