The bile phosphatidylcholine was radioactively labelled by intraperitoneal or intravenous injection of [3H]- or [14C]-palmitic acid into bile fistula rats. The radioactive bile was infused intraduodenally into other bile fistula rats. On an average, only 1.0% of the infused radioactive phosphatidylcholine fatty acid reappeared in bile phosphatidylcholine, whereas about 68% of simultaneously infused [3H]-taurocholate was recovered over the same period of time (6 hours). There is thus no significant enterohepatic circulation of intact biliary phosphatidylcholine.