Irritable bowel syndrome (IBS) is common in Caucasians and Japanese, but its epidemiology has not been studied in urbanized Chinese populations. Our aim was to compare diagnostic criteria and study the epidemiology of IBS in Hong Kong Chinese. In all, 964 subjects from public housing and 334 subjects from private housing were recruited for face-to-face interviews in Shatin, Hong Kong. A structured questionnaire was used to measure the prevalence of IBS according to the Manning, Rome I, and Rome II criteria. The SF-36 scale was used to measure quality of life (QOL) in subjects with IBS and in normal controls. The results were compared by the analysis of covariance (ANCOVA). Relevant medical consultations and absence from work were recorded. There was fair agreement between the Manning and Rome II criteria (K = 0.23; P < 0.001), but good agreement between the Rome I and Rome II criteria (kappa = 0.5; P < 0.001). The prevalence of IBS, based on the Rome II criteria, was 3.6% (95% CI = 2.0-5.2) in men and 3.8% (95% CI = 2.5-5.2) in women. Men with IBS had significantly lower vitality scores on the SF-36 scale than the controls (P < 0.05 by ANCOVA), and women with IBS had significantly lower mental health scores than controls (P < 0.05 by ANCOVA). In conclusion, IBS is quite prevalent in Hong Kong Chinese, and the QOL of subjects with IBS was significantly affected.