The authors made a clinical study of 80 cases of empyema who were diagnosed and treated at department of chest surgery, St. Mary`s Hospital, Chatholic Medical College, during the period of May.l964 through April.1969 and compared the empyema of infant and children with that of adults. 1. In age and sex ditribution, infant was 6 cases, childhood 22 cases and adult 52 cases. The ratio of male to female was 2.2:1. There`s a little difference in infant-childhood but prominence of males over females in adults was being 3. 3:1, in its ratio. 2. The cardinal symptoms were cough [61.3%], fever [60.0%] and dyspnea [52.8%]. The leukocytosis were observed in 83.7% of all cases, 96.2% of infant-childhood and 76.9% of adults. The hemoglobin level showed subnormal in 82.1% of infant-childhood and in 55.8% of adults. 3. Most frequent lesion to predisposing factor of empyema was pneumonia [43.7%],being prominent in infants children [64.3%] to that of adult 4. The Pathogenic organism by culture in 75 cases of empyema were staphylococuss [48%], streptococuss[9.3%], Gram[-] bacilli [9.3%], Klebsiella[2.7%], pneumococcus[4.0%], E. coli [5.4%] and no growth 21.3% in over all. Among the cases of empyema. staphlocal origin was 62.9% in infant-childfood and 39.6% adults. 5. Staphylococci were most susceptible to erythromycin [86. 1%], Kanamycin [75.0%], albamycin [61.7%] and neomycin [52.8%] but most resistant to penicillin, Chtoramphenicol and terramycin. 6. In the treatment of empyema, of 53 cases were closed thoracotomy drainage and the remainder of cases by open thoracotomy, decortication, thoracoplasty and pleuropneumonectomy. we could attain favourable results by only the closed thoracotomy in infant-childhood, 28 cases. 7. The mortality rate was 6.3% in over all; adult 3 cases, infant and children 2 cases. 3 cases of these, were due to staphylococcal infection.[KTCS 1969;1:41-49]