Limited evidence is available as to whether Kampo medicine modifies gastrointestinal function in humans. We investigated the effect of a Kampo medicine, Hange-koboku-to (Banxia-houpo-tang, HKT), on patients with functional dyspepsia (FD) and on healthy volunteers with regard to gastric motility. The gastric emptying rate (GER) in FD patients was significantly lower than in the healthy subjects. GER in FD patients and in healthy volunteers showed a significant increase after 2 weeks of medication with HKT. Furthermore, gastrointestinal symptoms improved significantly in the FD patients after the administration of HKT. These results suggest that HKT improves delayed gastric emptying and acts as a prokinetic agent.