In order to assess the use of Astronium urundeuva in folk medicine for treatment of diarrheal conditions, the alcoholic extract of its bark was tested on gastrointestinal transit in mice. The extract at oral doses of 100 and 200 mg/kg significantly inhibited physostigmine-induced gastrointestinal propulsion. Considering these data together with an in-vitro anti-acetylcholine effect reported earlier from this laboratory, we suggest that anti-cholinergic effects of the plant may account in part for its anti-diarrheal activity.