Topical myocardial hypothermia was maintained by Topical Cooling Device in 20 patients and by saline slush in 15 patients. Temperatures were assessed and recorded continuously on standardized locations for the right and left ventricular endocardium during 5 minutes periods. Mycoardial temperature of right ventricule was significantly lower in the saline slush group as compared to the TCD group for the first 5 minutes period. However, the differance during the second 5 minutes period was not significant. at the l0th minute, myocardial temperature of the left ventricule became significantly lower vvith TCD compared to saline slush. During the periods following the 10 th minute, the temperatures of the both ventricules were reduced to ideal temperature (1015 C) by TCD. Also, the myocardial hypothermia is an easy and safe modality especiaily in patients who need a long aortic crossclamping period during cardiac operations.