Previous studies have found no female predominance in irritable bowel syndrome (IBS) in non-Western countries. The aim of the study was to assess the prevalence and correlates of Rome II (IBS) in both sexes in Pakistan. A Population-based survey in a low-income inner city area using questionnaires to diagnose Rome II IBS and assess distress, disability and stressful life events. Data were collected from 880/938 (93%) randomly selected residents. 13.4% of women and 13.1% men met criteria for Rome II IBS; 34 (3.9%) had diarrhoea-predominant, 59 (6.7%) had constipation-predominant IBS and 24 (2.7%) had 'mixed IBS'. In logistic regression analysis, IBS was associated in men with high income (OR = 1.56; 95% CI: 1.05-2.3) and few years of education (OR = 2.17; 95% CI: 1.2-3.9) and in women with being married (OR = 3.6; 95% CI: 1.1-11.9) and stressful life events score (OR = 1.14; 95% CI: 1.01-1.3). Disability was associated with constipation-predominant IBS (OR = 1.99; 95% CI: 1.1-3.6), distress (OR = 1.19; 95% CI: 1.14-1.23) and stressful life events (OR = 1.19; 95% CI: 1.1-1.3). Investigations were more likely in men (54%) than in women (27%) (P = 0.003). These findings suggest that the equal sex ratio of IBS in urban Pakistan could result from a close association between marked distress and IBS in men similar to that found in women in western studies.