The present study investigated the effects of the herbal medicine Dai-kenchu-to (DKCT) and its 4 individual ingredients on intestinal blood flow (IBF) in rats by laser Doppler flowmetry. Intraduodenal administration of DKCT (30, 100 and 300 mg/kg) increased IBF in a dose-dependent manner, whereas the mean arterial blood pressure was not affected. One of the ingredients in DKCT is dried ginger rhizome (150 mg/kg), whose main component is [6]-shogaol (2 mg/kg), both of which showed similar effects to those shown by DKCT, while the other ingredients in DKCT only slightly increased IBF or had no effect. The calcitonin gene-related peptide (CGRP) receptor antagonist, CGRP (8-37), completely abolished the hyperemia induced by DKCT, dried ginger rhizome and [6]-shogaol. However, the vasoactive intestinal polypeptide (VIP) receptor antagonist, [4-Cl-DPhe6, Leul7]-VIP, and atropine were less inhibitory than CGRP (8-37), and the substance P (SP) receptor antagonist, spantide, had no effect. The present study demonstrated that DKCT and one of its active components, [6]-shogaol, produced an increase in IBF which was mainly mediated by CGRP and suggests that DKCT may be useful in the treatment of intestinal ischemia-related diseases.