SIRS, We read the article by Wilcox et al., and the letter by Kurien et al. with interest. We agree that bile acid diarrhoea (BAD) may be the underlying aetiology in a significant proportion of patients with chronic diarrhoea. With this in mind, we would like to share our own experience of this issue. We undertook a review of consecutive unselected new patient referrals to a single gastroenterologist’s out-patient clinic during a 3-year period, from January 2010 to December 2012. All clinic letters were reviewed retrospectively, and symptoms reported by the patient at the initial consultation were recorded. Radiology, endoscopy, chemical pathology, and histopathology databases were then cross-examined in order to ascertain the final diagnosis following full investigation, to the level deemed appropriate by the consulting physician. We defined BAD using a 23-seleno-25-homo-tauro-cholic acid (SeHCAT) retention value of <15% at 7 days. Of 613 consecutive unselected new patient referrals, 151 (24.6%) reported chronic diarrhoea. After investigation the final diagnoses are listed in Table 1. The second commonest cause of chronic diarrhoea, after irritable bowel syndrome (IBS), was BAD. Nine (45.0%) of 20 patients with BAD reported lower abdominal pain or discomfort. In 13 (65.0%) of these 20 patients there was no obvious cause of BAD, and these were classified as idiopathic, or type II, BAD. In summary, BAD was the commonest underlying cause of diarrhoea after IBS, and idiopathic BAD was commoner than coeliac disease among these patients. Almost 50% of patients with BAD reported lower abdominal pain or discomfort. Given that current symptom-based diagnostic criteria perform only modestly in predicting IBS, this may lead to misdiagnosis of BAD as IBS unless SeHCAT scanning is performed routinely, an issue identified by other investigators. 5–7 BAD should be considered as a likely diagnosis in all patients with chronic diarrhoea, and SeHCAT scanning should be moved up the hierarchy of diagnostic tests in such patients.