With advances in drug treatment of breast cancer, the number of patients experiencing cardiac toxicity or carcinomatous pericarditis is expected to increase. These conditions can cause cardiac tamponade, which is a potentially fatal condition requiring prompt diagnosis and treatment. We experienced 3 breast cancer patients with cardiac tamponade due to carcinomatous pericarditis who survived for prolonged periods after treatment with pericardiocentesis and intrapericardial instillation. The 3 women were 68, 46 and 46 years old, respectively, and receiving treatment for recurrent breast cancer after surgery. They developed dyspnea and cough and were diagnosed with cardiac tamponade by echocardiography. Pericardiocentesis was performed, and cytology of the effusion confirmed the diagnosis of carcinomatous pericarditis. Intrapericardial instillation of cisplatin reduced the cardiac effusion, ameliorating symptoms. The patients died 13, 31 and 14 months later, respectively. In our clinical review of 13 other cases of cardiac tamponade due to breast cancer, 85% achieved local control after the aforementioned local treatments, which were considered to be effective. Although the overall prognosis was poor with a median survival time of only 4 months, some patients were able to survive more than 1 year after local treatment with subsequent systemic therapy.