The possibility that the central and autonomic nervous system might be involved in the control of intestinal absorption was assessed by measuring the effect of psychological stress, induced by dichotomous listening, on jejunal transport in 15 healthy subjects. Using a triple-lumen perfusion technique to determine jejunal absorption, dichotomous listening significantly reduced mean net water absorption from 31.2 to 8.7 ml X 30 cm-1 X h-1 (p less than 0.005) and changed mean net sodium and chloride absorption to secretion (sodium +1.14 to -1.2 mEq X 30 cm-1 X h-1, p less than 0.01; and chloride +1.5 to -0.9 mEq X 30 cm-1 X h-1, p less than 0.02). During the hour following dichotomous listening these changes were maintained. Jejunal water, sodium, and chloride absorption measured in 9 subjects during three consecutive stress-free periods did not change significantly. Mean transit time over the 30-cm test segment, measured by a dye dilution technique, in 7 subjects was not significantly different during control and dichotomous listening periods, being 2.8 and 4.0 min, respectively. During the hour following dichotomous listening there was a significant increase in mean transit time to 6.4 min (p less than 0.02). In 7 subjects who received a constant intravenous infusion of atropine throughout the control, dichotomous listening, and recovery periods, jejunal sodium, chloride, and water absorption did not change significantly. These results suggest that psychological stress can influence jejunal absorption of salt and water and that this effect may be mediated by a cholinergic parasympathetic nervous mechanism.