Fifty-seven patients underwent 58 pericardiectomies for constrictive pericarditis during the 22-year period between 1958 and 1979. They were 43 males and 14 females with peak age incidence in the second decade, and 26.3% of them were children under 15 years. The etiologies of pericarditis were tuberculous in 40.3%, non-specific in 38.0%, pyogenic in 19.3%, and post-traumatic in 1.8%. Clinical features were alomost identical with those described in the other major reports. Pericardial calcification was noted in 29.8%, pleural change in 63.2% and enlarged cardiac shadow in 73.7% on the chest roentgenograms; atrial fibrillation in 15.8% and low voltage in 45.6% on the electrocardiograms. Venous pressures were elevated and circulation times prolonged. Right heart catheterization were performed in near half of the cases which revealed the characteristics of pericardial constriction. There were 7 deaths after surgery or the hospital mortality rate of 12.3%. The most common and fatal complication was arrhythmia, especially sudden cardiac arrest occurred in pyogenic pericarditis of children. Fifty patients manifested marked clinical improvement from early postoperative days and all were discharged from hospital in excellent condition. Follow-up observations were possible in 30 cases(60.0%) for the average period of one year seven months when all were completely free of symptoms and had normal physical examinations. Abnormal preoperative electrocardiographic changes also revealed the tend-ency toward normalization from early postoperative days except persisting T-Changes. The grave prognosis of pyogenic pericarditis in children and the importance on careful consideration about early pericardiectomy for active tuberculous pericarditis were stressed. And, discussion was also made on the correlation between clinical improvement and hemod ynamic changes after pericardiectomy. Special interest was placed on the preoperative electrocardiographic patterns resembling right ventricular hypertrophy in constrictive pericarditis and the mechanism of its return to normal after surgery.