Purpose:To evaluate the efficacy of treating malignant pleural effusion with S 311 anticancer vaccine by intrapleural injection.Methods:62 cases with malignant pleural effusion,after drainage, S 311 anticancer vaccine 0.16 mg was injected into the pleural cavity in therapy group (T),and cisplatine 40 mg/m 2 in control group (C).The treatment was repeated after a week , then the efficacy, quality of life, survival rate and toxicities was evaluated.Results:The response rate was 90.6% in T group and 60.0% in C group. There was statistical difference between the two groups ( P