A study was undertaken to compare desflurane- and isoflurane-based anaesthesia in patients undergoing day-care arthroscopic surgery. Anaesthesia was induced with propofol 2-3 mg.kg-1 and a laryngeal mask airway was inserted after loss of the eyelash reflex. Patients were then randomly divided into two groups to receive maintenance anaesthesia with either isoflurane or desflurane delivered in oxygen and nitrous oxide. Alfentanil was used as the analgesic during the operation. Early recovery was assessed by measurement of the times to eye opening, extubation and ability to give a date of birth. Psychomotor recovery was assessed by performance on the finger tapping and perceptive accuracy tests. Mood was evaluated using visual analogue mood scores and the mood adjective checklist. Discharge times were also measured. Early recovery was significantly quicker following desflurane anaesthesia but no differences between the groups were found in psychomotor tests. The mood adjective checklist showed that patients in the isoflurane group had a greater total mood score and were more calm than those in the desflurane group; this was particularly evident 2 h after anaesthesia. The discharge times were similar for the two groups. Desflurane is a satisfactory alternative to isoflurane for day care anaesthesia.