The effects of lumbar epidural anaesthesia and two types of general anaesthesia on blood loss and haemodynamics during and after hip replacement were compared in three groups of patients. One group (n = 14) received continuous lumbar epidural anaesthesia, another group (n = 10) was given inhalational anaesthesia and spontaneous breathing after endotracheal intubation, and the third group (n = 14) received artificial ventilation after intubation and pancuronium and fentanyl intermittently i.v. Intra-operative blood loss in patients under epidural anaesthesia was 950 +/- 300 ml (mean +/- SD) and blood loss during the following 24 h-i.e. as long as the epidural anaesthesia was maintained-was 370 +/- 80 ml. These figures were significantly lower than the intra- and post-operative blood losses in patients under general anaesthesia with narcotics as post-operative pain treatment: 1140 +/- 200 ml (inhalational anaesthesia) followed by 480 +/- 70 ml and 1540 +/- 340 ml (artificial ventilation) followed by 500 +/- 110 ml. The intra-operative blood loss in the general anaesthesia group with spontaneous breathing was significantly smaller than the blood loss in the artificially ventilated group, whereas the post-operative blood loss in the two general anaesthetic groups was similar. Haemodynamic differences explain these differences in blood loss. Thus epidural anaesthesia induced hypotension on the arterial and venous sides. Intra-operatively, inhalational anaesthesia also induced hypotension on the arterial and venous sides compared with general anaesthesia using artificial ventilation. Post-operatively, the general anaesthesia groups behaved haemodynamically similarly and no differences in blood loss were seen. The reduction in blood loss, notably associated with lumbar epidural anaesthesia, is beneficial in decreasing the hazard and cost of blood transfusion.