Abstract: Abstract From January 1990 to May 1993, we treated patients of lung cancer with hydrothorax by intubation of pleural cavity and sealing drainage of hydrothorax plus anticarcinogen injection intothe pleural cavity' The patients are divided into two groups--drainage and control (routine pleuralcentesis and pleural cavity anticarcinogen injection) group, and 30 cases in each group. All ofthe patients got confirmed diagnosis by hitology or cytology examination, and the KPS (KarnofskyPerfomnce Scale) of each patient is no less than 60 Points' All patients are treated for the firsttime. In the drainage group, there are 7 CR cases and 20 PR cases, the total effective rate is 90K 1but in the control group, only 3 CR cases and 12 PR cases, its total effeCtive rate is 50N. Thereare highly significant differences between the two groups by statistical analysis (X²=11. 4285, P0. 01 ). Since the drugs used in the two groups are not completely the same,we used equal dosesof DDP as the comparision. Among the 21 cases in the drainage group, 5 got CR, 14 PR, the effective rate is 90. 4% i but in the control group, among the 21 cases, only 2 got CR PR and 9 PR,its effective rate is 52. 3%' The statistical analysis showed that the two groups had hashly sgnificant differences (X² = 7. 466, P0.01 ). Our result showed that the curative effect of the drainagegroup is better than the control group, and the drdsage method is worthy of spreading.