Chronic massive pericardial effusion without cardiac tamponade is relatively rare. Nearly half of all patients with chronic large pericardial effusion are asymptomatic. We report a case of a 77-year-old man who presented with an asymptomatic chronic massive pericardial effusion, with no evidence of cardiac tamponade or pericardial constriction during a 10-year follow-up. The patient had a complex history of lymph node tuberculosis, hypertension, hypothyroidism, and polycythemia vera, as well as high-dose P-31 radiation exposure 45 years ago. There was no evidence of tuberculosis infection, hypothyroidism, malignant tumor, severe heart failure, uremia, trauma, severe bacterial or fungal infection, chronic myeloid leukemia, or bone marrow fibrosis after admission. The patient underwent pericardiocentesis twice. The pericardial effusion comprised exudate fluid with a high proportion of monocytes. The patient refused indwelling catheter drainage or pericardiectomy. The likely final diagnosis was recurrent chronic large idiopathic pericardial effusion.