We report a case of metastatic plasmacytoma to the myocardium and coronary vessels in a 57-year-old man with multiple myeloma. Originally, the patient had a large plasmacytoma in his left chest wall and lung. He received local radiation and chemotherapy. Subsequently, the patient presented with symptoms of congestive heart failure. He had no prior history of cardiac disease. The patient was treated medically and later died from respiratory failure. At autopsy, a metastatic plasmacytoma was identified within the myocardium and externally compressing the coronary arteries. The tumor infiltrated into the coronary sinus. It is difficult to speculate whether the patient's symptoms were due to cardiac involvement since the tumor burden in his chest was also considerable. To our knowledge, coronary vessel involvement with plasmacytoma has not been previously described.