The influence on mood of anaesthesia by infusion with propofol or methohexitone was evaluated in 80 female patients assessed with the Profile of Mood State preoperatively and at 30 min, 1, 2 and 4 h after anaesthesia. Patients given propofol were more elated and continuously less anxious than those given methohexitone from 1 to 4 h after anaesthesia (54.3, SEM 1.1 vs. 50.7 SEM 1.2). They also felt more agreeable after 2 h (45.4 SEM 1.4 vs. 48.4 SEM 1.2). All patients felt more tired and more confused post-operatively than pre-operatively. Propofol has different and more favourable influences on the post-operative mood state than does methohexitone.