Upper small bowel motility was continuously recorded for 36-48 h in 37 healthy ambulant volunteers using twin pressure-sensitive radiotelemetric capsules tethered in the small bowel. Each study began with a 24-h period that was free of applied stress. The second 24-h period included 7 h of intermittent psychological stress during the day and brief episodes of acute stress during the following night, except in the members of a control group to whom no stress was applied. Stress responses were assessed from cardiovascular status and self-reported visual analogue scales. Applied stress during the second day significantly inhibited the incidence of fasting migrating motor complexes compared with the first day; when no stress was applied there was no reduction in migrating motor complexes. Nocturnal stress was less effective in the inhibition of migrating motor complexes. All the stressors induced positive cardiovascular and subjective stress responses. The stress-induced inhibition of migrating motor complexes was reversed by oral metoclopramide; however, the drug did not reverse the cardiovascular or subjective response to stress. In contrast, domperidone did not inhibit the gastrointestinal effects of stress. Neither drug appeared to influence small bowel motility under normal conditions.