Irritable bowel syndrome (IBS) is a common gastrointestinal disorder. Characterised by abdominal pain or discomfort, bloating and altered bowel habit, IBS is a chronic recurring condition, typically affecting up to 15% of the Western population, IBS can be subclassified into IBS with constipation (IBS-C), IBS with diarrhoea (IBS-D), or IBS with alternating constipation or diarrhoea symptoms (IBS-A). Conventional clinical diagnosis focuses on excluding all potential organic causes of patient symptoms. However, a positive diagnosis of IBS may be established using published criteria such as the Manning and/or Rome criteria. While these methods are useful to identify patients with IBS who are suitable for enrollment into clinical trials, the criteria are relatively complex and not readily applicable to general practice. In this review we present an 'identify, eliminate, probe' algorithm that may be appropriate to establish a positive diagnosis of patients with IBS-C, as symptoms characteristic of patients in this IBS subgroup are least likely to be confused with symptoms reflecting serious organic disease.