The purpose of this review is to review current studies of cannabinoids and the urinary bladder. Cannabinoids have been identified in the urinary bladder and are purported to play a modulatory role in detrusor overactivity (DO) as there is a change in the expression of cannabinoid receptors (CBR) in these patients compared to healthy controls. Studies using knock-out mice suggest sensory urodynamic endpoints can be modified by activation of the CBR. Clinical studies demonstrated that Cannabis improves urgency in patients with neurogenic DO. CBR are involved in micturition at both peripheral and CNS sites. CBR expressed in afferent fibre endings in the urothelium could influence bladder function. CBR agonists may be useful for future treatment of DO as there is altered CBR expression in these bladders. In addition, FAAH-2 has been localised in human bladder and future studies may show that this enzyme has a role in bladder dysfunction.