The involvement of the pericardium by metastatic tumors is not uncommon, particularly in patients with lung cancer, breast cancer, lymphomas, leukemias, and melanomas. There are five therapeutic modalities for the treatment of malignant pericardial effusion, including pericardiocentesis, pericardial sclerosis, systemic chemotherapy, radiotherapy, and surgical treatment. The optimal treatment selection is dependent principally on a patient's life expectancy; responsiveness of the tumor to chemotherapy, irradiation, or both; and whether or not cardiac tamponade is present at diagnosis. The overall prognosis of patients with malignant pericardial effusion is primarily influenced by the extent and histologic features of the underlying cancer. Although this condition is usually incurable, a reasonable period of useful palliation can be obtained in most patients.