The effect of Daikenchuto, a traditional herbal medicine, on gastrointestinal hypoperistalsis in postoperative ileus (POI) was investigated. POI was induced by laparotomy with manipulation of the gastrointestine under anesthesia, and gastrointestinal transit was calculated by migration of Evans blue. Daikenchuto (270 - 2,700 mg/kg, p.o.) dose-dependently improved the delayed gastrointestinal transit in POI. This effect of Daikenchuto was partially inhibited by SB204070 (1 mg/kg, s.c.), a 5-hydroxytriptamine(4) (5-HT(4))-receptor antagonist and completely abolished by atropine (1 mg/kg, s.c.), a muscarine-receptor antagonist. Among the constituents of Daikenchuto, the medical herb zanthoxylum fruit (60 mg/kg, p.o.) and maltose syrup (2,400 mg/kg, p.o.) significantly ameliorated the delayed gastrointestinal transit, but ginseng and processed ginger did not affect the gastrointestinal transit in the rat POI. The improvement induced by zanthoxylum fruit was also inhibited by atropine or SB204070. In addition, the high osmotic pressure of the maltose syrup (2400 mg/10 mL per kg) was related to the improvement of delayed gastrointestinal transit. These results demonstrated that Daikenchuto ameliorates postoperative hypoperistalsis via cholinergic nerves and 5-HT(4) receptors and that osmotic pressure also may be involved in this action. Moreover, zanthoxylum fruit and maltose syrup were crucial medical herbs contributing to the ability of Daikenchuto.