A retrospective study was carried out on anaesthetic records concerning spinal anaesthesia with hyperbaric bupivacaine 0.5% in urologic surgery. Three doses were utilised: slight (< 0.19 mg.kg-1), mean (0.19-0.21 mg.kg-1) or important (> 0.21 mg.kg-1) for two different levels: T12 or T10. Important doses may be involved excessive extension. Failures are perhaps more frequent with slight doses. Mean doses, 0.20 mg.kg1, seems to be recommended.