The concentration of myoglobin in plasma was assessed before and up to 68 hours after tourniquet release in 27 patients who underwent elective operations with no incision into skeletal muscle. The duration of ischemia was 1-3 hours. A control group underwent the same kind of surgery without the use of tourniquet. There was a minimal elevation in myoglobin values after 65 and 90 minutes of ischemia, and a marked elevation after more than 150 minutes of ischemia. Maximum values were reached 8 to 10 hours after tourniquet release, and preoperative values after 50 to 60 hours.