BACKGROUND/AIMS: It is uncertain what difference exists in the rectal motor and sensory characteristics between the diarrhea-predominant (D-IBS) and constipation-predominant (C-IBS) IBS subgroups. Our aim was to investigate the differences in the compliance, sensitivity and postprandial response of the rectum between the D-IBS and C-IBS patients. METHODS: Twenty-one D-IBS patients, sixteen C-IBS patients and fourteen healthy controls participated in this study. Using a barostat, sequential isobaric rectal distensions were performed, and then the postprandial change of the rectal tone was evaluated. Subsequently, the isobaric rectal distensions were repeated. RESULTS: While no differences in rectal compliance and the prevalence of hypocompliant rectum between two subgroups were observed during the fasting period, the D-IBS patients exhibited lower rectal compliance and a higher prevalence of hypocompliant rectum in the postprandial period compared to the C-IBS patients. A significant postprandial decrease of rectal compliance was observed in the D-IBS patients, but not in the C-IBS patients. No differences were observed between the subgroups in the threshold pressures for discomfort or pain, the prevalence of hypersensitive rectum and the response of rectal sensitivity to a meal. The postprandial increase of the rectal tone was significantly lower in the C-IBS patients, as compared with D-IBS patients. CONCLUSIONS: The symptom-based subgrouping of IBS is related to the responsiveness of rectal compliance and tone to a meal.