Abstract: cases of thoracic echinococcosis were surgically treated by endocystectomy(79%),pneumonectomy(12%),drainage and other operations(9%).Among a total of 1 010 opera-tions,the mortality was 0.6%( 5/807).Of 637 cases received 798 endocystectomies,the re-currence rate was 4.2%(27/638).Up to 1979,the first series of 323 cases were followed-upfor 3-20 years,no single case died of thoracic echnococcosis,Among the ,32 non-operation cas-es,the mortality was 22.2%(6/27) and 9 cases were spontaneously cured.22 cases were given praziquantel at two dosages,Group A received 120-150 mg/kg andGroup B received 210 mg/kg in divided doses for 5-6 days.The death rate of protoscolices in-side the operatively removed cystic fluid from the above two groups was 43.1±9.6% and64.2±3.5%,respectively,while in the untreated Group C.2±2%(P0.01).With totaldosage of praziquantel 300 mg/kg in divded doses for 7 days,the concentration of praziqantelin patient's blood and cystic fluid was 0.49±0.075 μg/ml and 0.006μg/ml,respectively.