Serum myoglobin concentrations were studied in 46 patients during orthopedic and plastic operations that required the application of a pneumatic limb tourniquet. Serum myoglobin was measured at preoperation, during tourniquet and after touriquet release. In the general anesthesia patients, serum myoglobin was after tourniquet release(172.72+/-29.49 ng/ml) significantly increased(p<0.01) than at preoperation(103.06+/-24.03 ng/ml). In the regional block patients, serum myoglobin after tourniquet release(117.69+/-10.08ng/ml) also increased(p<0.05) than at preoperation(67.08+/-14.99ng/ml). In the male patients, serum myoglobin was significantly increased(p<0.05) during tourniquet and after tourniquet release(123.36+/-15.42ng/ml & 158.86+/-21.10ng/ml) than at preoperation (93.58+/-17.11ng/ml). In the female patients, there was no significant difference to regardless of tourniquet application. In the patients that tourniquet application time was within one hour, serum myoglohin was significantly increased(p<0.01) during tourniquet and after tourniquet release(125.66+/-18.86 & 126.20+/-14.99ng/ml) than at preoperation(86.12+/-15.29ng/ml). In the patients that tourniquet application time was over one hour, serum myoglobin was sig- nificantly increased(p<0.01) during tourniquet(l05.92+/-21.84ng/ml) than at preoperation(91.16+/-31.17ng/ml) and in the after tourniquet release(183.88+/-40.96ng/ml), serum myoglobin was more significantly(p<0.05) increased than during tourniquet.