Intestinal secretion is enhanced by starvation in rats. The rectum from fed and 3-day-starved rats generates a basal electrogenic ion transfer (short-circuit current) in vitro which is mainly electrogenic Na+ absorption (amiloride-sensitive, 66-71%) with a small component of electrogenic chloride secretion (furosemide-sensitive, 14-22%). Bethanechol, a muscarinic agonist, caused an increase in the short-circuit current (mainly furosemide-sensitive chloride secretion) and potential difference in rectums from both fed and starved rats but the respective values for the starved animals were 100% and 64% greater. In starvation, the rat rectum is an indicator of intestinal secretory status. The result warrants investigation of human rectal electrogenic secretion in nutritional deprivation.