Post-operative delirium is seen after long-duration surgery such as vascular and orthopedic surgical procedures with higher incidence. Delirium is associated with higher post-operative mortality, morbidity and delayed functional recovery. Advanced age, post-operative pain and sleep problem were important factors for delirium. Therefore post-operative analgesia and good sleep can help to prevent post-operative delirium. The use of intraoperative regional anesthesia does not certain to decrease the incidence of post-operative deliryum when compared with general anesthesia. Neuroleptics such as haloperidol, droperidol and benzodiazepines are used in order to control symptoms like restlessness, agitation and altered perceptions. We aimed to discuss in this case post-operative delirium that developed after open prostatectomy and cystolithotomy under spinal anaesthesia.