Following a review of the literature for non-cholinergic, non-adrenergic mechanisms that are assumed to play a part in regulating the function of the lower urinary tract, some methods of neuropeptide research are described to determine the actual distribution and concentration of these substances. Prominence in the group of nonopioid peptides is given to VIP for the experimentally founded part it plays as relaxation mediator and the probable effect it produces in reducing the spontaneous detrusor activity. Opioid peptides, on the other hand, exercise influence over bladder capacity regulation. There is sporadic clinical evidence for the part certain neuropeptides may play in giving rise to bladder instability. Further studies are invited to add a new aspect to the aetiology and therapy of the relevant pathologic conditions.