Previous experiments suggested differences in the bile salt independent flow rate between monkeys and dogs, and in the ability of bile salt secretion to influence bile flow. The present study was performed to determine whether the availability of food could have influenced these results. Bile flow and bile salt secretion rates were studied in fasted and fed primates. In the fasting experiments, sodium cholate, sodium taurocholate, and monkey bile were infused into the duodenum; only sodium cholate was infused in the feeding experiments. The results showed that bile flow was linearly related to the bile salt secretion rate in both fasting and feeding animals. Bile salt independent flow is extremely variable during fasting and is increased and stabilized by feeding. These studies indicate that the differences found in previous experiments are probably attributable to variations in experimental design.