Pericardial disease developed in 31 patients with a variety of malignancies. Half of the patients (58 percent) were found to have malignant pericardial involvement, 32 percent idiopathic pericarditis and 10 percent radiation-related pericarditis. Facial swelling, cardiac arrhythmias and pericardial tamponade occurred frequently in the patients with malignant pericardial disease. Fever, pericardial friction rub and improvement with nonsteroidal anti-inflammatory drugs characterized the patients with idiopathic pericarditis. Effusive-constrictive pericarditis requiring pericardiectomy was noted in patients with radiation-induced disease. Pericardiocentesis documented malignant pericardial disease in 85 percent of patients studied, while 15 percent required open biopsy for diagnosis. Specific therapy directed at malignant pericardial disease may contribute to survival up to one year in 25 percent of patients. In 40 percent of patients with idiopathic pericarditis and in the majority of patients with radiation-induced pericarditis, survival was one year with specific therapy. A systematic evaluation of pericardial disease will benefit a subset of cancer patients with idiopathic pericarditis and radiation-induced pericarditis who can be managed conservatively.