Inflammatory Bowel Disease (IBD; Crohn's disease and ulcerative colitis (UC)) is a condition of unknown aetiology that seriously affects gut function. Gastrointestinal activity is regulated through the release of different neurotransmitters, many of which are neuropeptides. Two peptides which regulate gut secretion are the endogenous opioid peptide, dynorphin A(1–8)which reduces secretion and vasoactive intestinal polypeptide (VIP) which is prosecretory. Nitric oxide (NO) also stimulates intestinal secretion and is produced as a result of the activity of nitric oxide synthase (NOS) enzymes. Some neurotransmitters are released from neuroendocrine (NE) cells found in mucosal crypts and perturbations in the numbers of these cells have been noted in IBD. This investigation used immunohistochemistry to identify populations of NE cells in normal colon and in IBD. NE cells were visualized using an antibody raised against the specific neuroendocrine marker chromogranin A. Sub-populations of cells were further classified into those staining positive for neuronal NOS, VIP or dynorphin A(1–8). The number of NE cells is reduced in both Crohn's disease and UC. However the relative proportion of cells positive for nNOS, VIP and dynorphin A(1–8) was increased in both forms of IBD.