Irritable bowel syndrome (IBS) is a common functional bowel disorder. Along with other factors diet plays an important role in the causation of IBS. This population-based study was done to find out the prevalence of IBS and to find out the dietary factors associated with IBS from August 2011 to December 2011 in Sylhet district of Bangladesh. Nineteen hundred apparently healthy subjects selected by cluster sampling methods were interviewed by a validated bowel disease questionnaire. Dietary history of the subjects was also taken. Irritable bowel syndrome was diagnosed according to Rome III criteria. The prevalence of IBS was found 14.2% (n=269, M=15%, F=13.4%, p=0.365). Mean age of the IBS patients were higher than the study population (41.35 years vs. 34.74 years, p=0.000). Irritable bowel syndrome was found more in low education group (16.3%) with lower socioeconomic status (16.5%) and in single person (16.7%). IBSD was the most prevalent subtype (48.7%), IBSM was the next common subtype. Abdominal pain relieved by defecation (81%) and abdominal pain associated with loose stools (81%) were the two commonest symptoms. Age (OR 1.023, p=0.000), less intake of meat (OR 2.281, p=0.000) and pulses (OR 1.648, p=0.001) and more intake of tea (OR 1.524, p=0.009) and spices (OR 0.452, p=0.000) were found as independent predictor of IBS. Irritable bowel syndrome is a common disorder in our community. IBSD is the most prevalent subtype. Less intake of meat, pulses and more intakes of tea and spices are important associated factors for IBS.