The rate of failed spinal anaesthesia, defined as the need for unplanned general anaesthesia, was evaluated in a prospective study involving 137 patients undergoing transurethral resection of the prostate (TURP). The incidence of sensations at the operative site which did not require general anaesthesia was also evaluated. Attention to details was emphasized in the technique. Patients randomly received either hyperbaric Niphanoid tetracaine (n = 74; 6 or 10 mg) or hyperbaric bupivacaine (n = 61; 6 mg), with or without adrenaline. General anaesthesia was necessary in one patient (0.72%). Twelve additional patients reported sensations at the operative site which were rapidly relieved by light intravenous supplementation with low doses of fentanyl and/or thiopentone. The patients reporting sensations did not differ in demographic characteristics, spinal technique, local anaesthetic, or degree of sensory or motor blockade. Addition of adrenaline to the 6-mg doses of both tetracaine and bupivacaine decreased the incidence of sensations at the operative site.