['Colonic and rectal biopsies, often taken from an endoscopically normal large bowel, form a significant proportion of the histopathology workload. The aim of this study was to determine diagnostic yield from mucosal biopsies in patients with normal colonoscopy or sigmoidoscopy, and whether or not diarrhoea is predictive of abnormal histology.', 'A retrospective analysis of pathology requests, endoscopy and pathology reports taken during 1 year was undertaken in a tertiary care hospital for all biopsies from endoscopically normal ileal, colonic and rectal mucosa. Of 626 patients fulfilling inclusion criteria, 602 had at least one colonic or rectal biopsy. Colorectal histology was abnormal in 65 (14.5%) of 447 patients with diarrhoea, while of 155 patients without diarrhoea, histology was abnormal in 17 (11%; P=0.41). Patients older than 60 years had a markedly increased likelihood of a specific histological abnormality [odds ratio 2.76 (1.30-5.79); P=0.0045]. Diagnoses included microscopic colitis, distorted mucosal architecture consistent with inflammatory bowel disease, ischaemia, polyps, mucosal prolapse and schistosomiasis.'] Are specific histological abnormalities more likely in biopsies of endoscopically normal large bowel after the age of 60 years?