Fifty unpremedicated patients scheduled for outpatient restorative dentistry and/or oral surgery lasting 2 to 4 h were anaesthetized with either propofol infusion or isoflurane inhalation. Before induction of anaesthesia with propofol (2.5 mg.kg-1), all patients were given 75 mg of diclofenac and 0.01 mg.kg-1 vecuronium intravenously. Intubation was facilitated with suxamethonium (1.5 mg.kg-1) and anaesthesia was maintained in random order either with propofol infusion (12 mg.kg-1.h-1 for the first 20 min, 9 mg.kg-1.h-1 for the next 20 min, and 6 mg.kg-1.h-1 for the rest of the anaesthesia) or with isoflurane (inspired concentration 1-2.5%), both with nitrous oxide and oxygen (30%). The patients breathed spontaneously using a non-rebreathing circuit. Patients given propofol infusion became re-orientated faster (11.0 +/- 5.5 min vs. 16.5 +/- 7.5 min; P less than 0.01) and at 30 min walked along a straight line better (P less than 0.01). At 60 min, none of the propofol patients displayed an unsteady gait, whereas 11 of the 25 isoflurane patients did (P less than 0.001). None of the patients receiving propofol had emesis at the clinic, compared with 10 of the 25 patients receiving isoflurane (P less than 0.001). The overall incidence of emesis was 2 of 25 and 14 of 25 in the propofol and isoflurane groups, respectively (P less than 0.01). Patients receiving propofol were discharged home earlier than patients receiving isoflurane (80 +/- 14 min and 102 +/- 32 min, respectively; P less than 0.01). It is concluded that propofol allows early discharge of patients, even after long anaesthesias.