SummaryThe uptake of enflurane at a constant end-expired concentration of 2% in oxygen was studied in 38patients, ASA I or 2, undergoing elective orthopaedic procedures. The anaesthetic was administered using a computer-controlled closed circle system, Following an initial 4 min period during which the expired concentration of enflurane was established, the rate of uptake of enjlurane showed a triexponential decline. The mean cumulative use of enflurane after 60min was 10.7m1, and after 120min was 18.4ml.