Objective To study the therapeutic effect of tumour infiltrating lymphocytes (TIL) on malignant pleural effusion in aged cancer patients. Methods TIL cultured and amplified product of cancer patient's own malignant pleural effusion was used for treatment in aged cancer patients by intrapleural injection once every other day for at least four times. Results In 21 cases treated, lymphocytes in pleural effusion increased, while tumour cells gradually decreased, and pleural effusion gradually absorbed. After 1 month 19 cases were effective (90 5%). Conclusions Auto pleural effusion tumour infiltrating lymphocytes might be effective for malignant pleural effusion.