The effects on bile secretion of classical stimulants and depressants of the parasympathic system were reinvestigated in the anaesthetized rat. Antimuscarinic drugs and vagotomy did not decrease bile flow; acetylcholine and 2-deoxy-D-glucose did not increase bile flow; insulin-induced increase in bile flow was not suppressed by vagotomy. These results do not support the hypothesis of a short-term vagal control of biliary secretion in the anaesthetized rat.