OBJECTIVE The accuracy of ileo-anal pouch biopsy reporting was assessed. METHODS The pathology reports of 100 consecutive pouch biopsies were reviewed to assess the accuracy and consistency with which the St Mark's histological scoring criteria were applied. The quality of pouch biopsy sampling and provision of clinical and endoscopic information on pathology request forms was also assessed. RESULTS In 27% of cases no relevant endoscopic or clinical information was provided with the pathology request form. Separately labelled biopsies from the prepouch ileum, pouch and columnar cuff were submitted in only 4% of cases. In 32% of pathology reports, no acute or chronic St Mark's score was included. In 2% of cases the St Mark's scoring criteria were applied inappropriately. Twenty per cent of cases histologically diagnosed as pouchitis did not include a numerical score. In 30% of cases diagnosed histologically as pouchitis, an acute inflammatory score of < 4 (i.e. insufficient for this diagnosis) was included in the report. CONCLUSIONS Pouchitis is a combined clinical, endoscopic and histological diagnosis. The correct interpretation and application of the St Mark's histological scoring criteria for pouch biopsies is an important part of this diagnostic process.