It has been suggested that giant ganglia are a marker for a developmental bowel disorder, intestinal neuronal dysplasia of the submucosal plexus (IND B), diagnosed in a proportion of patients with severe intractable constipation. Diagnosis of this condition, however, remains controversial with a wide variation in the frequency of diagnosis in different centres. Our aim was to assess the frequency with which giant ganglia could be found in the bowel of individuals who did not give a history of life-long constipation. We also aimed to assess the reproducibility of giant ganglia counts. For this two pathologists independently assessed pieces of normal bowel taken away from the site of the lesion in patients who had undergone surgery for colorectal carcinoma. Giant ganglia containing seven or more ganglion cells were found in 76 and 78% of subjects by each of the two pathologists. There was 1 giant ganglion per 10 ganglia counted in those patients in whom they were identified and 1 giant ganglion per 10.9 ganglia overall. Sections from eight patients in whom there was a history of constipation and/or melanosis coli did not show a greater number of giant ganglia. We conclude therefore that so-called "giant ganglia" are a common feature in the submucosa of normal bowel and that the presence of occasional giant ganglia cannot be considered diagnostic of IND B.