Clinical studies of 60 patients hospitalized with pericarditis during the period of Jan. 1973 to Dec. 1977 are presented. Acute effusive pericarditis appeared in 34 patients and chronic constrictive pericarditis in 26 patients, of which incidences were not different between males and females but most commonly occurred in second and third decades. Unfortunately the cause of pecicarditis was unknown in 20 patients. However, the bacterial agents and tuberculosis are the most common causes of acute effusive and chronic constrictive pericarditis respectively. Histopathologic examinations were performed in 25 patients of which findings were non-specific inflammation with or without organization, tuberculosis, malignant neoplasm and suppuration in order of frequency. The subjective symptoms and signs were dyspnea, cough, chest pain and fever with chillness in acute effusive pericarditis and dyspnea, cough and peripheral edema in chronic constrictive pericarditis. The combined diseases were observed in 30 patients which were found to be associated etiologically with the pericarditis in 28 patients. The gross findings of pecicardial fluid observed in 40 patients were not characteristic regarding to its etiology except purulent in becterial and bloody in maligmant neoplastic pericarditis. The findings of chest P-A were diagnostic in 20 patients of 60. The Echocardiographic findings examined in 8 patients with acute effusive pericarditis were diagnostic in all. The electrocardiogram showed low voltage, flat or inverted T-wave, sinus tachycardia and electrical alternans in order of frequency in both acute effusive and chronic constrictive pericarditis. Of the 31 patients treated medically 21 patients were improved, 6 were in fair and 4 died. Of the 27 patients treated surgically to include pericardiectomy and pericardiotomy 21 patients were improved and 6 died.