The perioperative total serum CK and CK-MB activities were determined in 38 patients with carcinoma of the esophagus and cardia of the stomach with fluorometric and cylinder layer chromatography. The data were compared with those obtained from 18 patients undergoing pulmonary operation and 20 normal subjects. The results suggest that: (1) carcinoma of the esophagus and cardia of the stomach could not induce variation of the total serum CK and CK-MB; (2) the elevation of the total serum CK after esophagogas-trostomy might probably be due to the trauma of the skeletal muscles of the chest wall;(3)the total serum CK is non-specific for the diagnosis of AMI in the perioperation period,but CK-MB might be considered as a specific enzyme criteria.