BACKGROUND/AIMS: Functional dyspepsia (FD) is a common disease but there is no established treatment. Rikkunshito is a traditional Japanese medicine that is widely used for treating upper gastrointestinal symptoms and its effect on ghrelin is of great interest. The aim of this study was to investigate the effect of rikkunshito on upper gastrointestinal symptoms and the levels of acylated ghrelin (AG) in patients with FD. METHODOLOGY: This study was a paralleled, randomized controlled trial. Patients were treated with either rikkunshito (group R) or domperidone (group D) for 4 weeks. The overall change in dyspeptic symptoms was evaluated by the GSRS (Gastrointestinal Symptom Rating Scale) questionnaire score. RESULTS: 27 patients were enrolled. There was a significant improvement in dyspeptic symptoms in both groups, based on the GSRS score. AG levels increased significantly in plasma in group R at 2 weeks after treatment (paired t-test, p<0.05). The improvements of reflux (Pearson's correlation test, r=-0.73, p=0.04) and indigestion (r=-0.76, p=0.03) symptoms in group R showed a good correlation with the increase of AG. CONCLUSIONS: Rikkunshito improves upper gastrointestinal symptoms in patients with FD, accompanied by an increase in the levels of AG.