A 74-year-old male developed cardiac tamponade due to malignant pericardial effusion six months after he was diagnosed as primary lung cancer. Carboplatin was administered into the pericardial cavity six times with the total dose of 1,100 mg. Pericardial effusion disappeared without severe toxicities and response duration was about three months. Upon recurrence, he was again successfully treated with single intrapericardial administration of 300 mg of carboplatin. He survived for seven months after being diagnosed as cardiac tamponade.