TRADITIONALLY, metastases to the heart have been considered to be a clinical curiosity or an incidental finding at the autopsy table. At the Laboratory of Experimental Oncology we have had the opportunity to follow to necropsy 288 patients with advanced neoplastic disease of wide variety. It has been our clinical impression that cardiac metastasis in patients with advanced neoplastic disease is of greater frequency and is more of a clinical problem than is generally recognized. The frequency of secondary neoplasms of the heart, as reported in the literature, has been between 1 and 11% of patients with neoplastic diseases who have come to autopsy. Table 1 summarizes the frequencies as found in four large series. It is noteworthy that the reported frequency is considerably higher during recent years, probably reflecting increased interest in the problem. Another possible reason for the progressively higher frequency is that patients with advanced neoplastic disease