From September 1983 to February 1987, 45 consecutive aortic valve operations were performed using the retrograde continuous cold blood cardioplegia (RCCBC) via the coronary sinus. Except one patient died of stuck valve after aortic and mitral valve replacements, 44 patients were subjected for this study and all survived patients were symptomatically improved. They were divided into two groups according to the aortic cross clamps time (ACCT). Group 1; 23 patients, ACCT within 120 minutes, and Group 2; 21 patients, ACCT exceeding 120 minutes. After the operation blood was taken periodically to check creatine phosphokinase (CPK) and its iso-enzyme creatine-kinase (CK-MB) and GOT etc. Then their levels were compared between the two groups. Although there seemed to be a tendency that the highest levels of these enzymes increase according to the ACCT, there was no significant difference in CK-MB level between the two groups. Judging from the operative results and the postoperative study of enzymatic level, RCCBC is safe and useful for aortic valve surgery, especially when long ACCT is necessary for correcting complicated lesions or when the coronary orifice is not suitable for coronary perfusion in aortic dissection.