Background : Lung cancer is the leading cause of malignant pleural effusions, which is currently most commonly treated using pleurodesis via bedside thoracostomy. Several agents had been used for the treatment of pleural sclerosis, but with differing efficacies and associated side effects. Our purpose with this study was to compare the efficacy, side effects and disease free survival times of patients being treated with OK-432 and doxycycline sclerotherapy in lung cancer induced malignant pleureal effusions. Materials and Methods : 79 patients who underwent pleurodesis with OK-432 and doxycycline, between Jan.1994 and Aug. 2001, were retrospectively reviewed. Response 30 days following pleurodesis were determined from chest radiographs, with the disease free survival time being evaluated according to the response. Results : The success rates, 30 day followint pleurodesis, with OK-432 and doxycycline 83 and 87%, respectively (p=0.677). With regard to the side effects, fever was more common when OK-432 was used (59%, p=0.001), and pain was more common with doxycycline use (73%, p=0.008). There was no significant difference in disease free survival times between OK-432 (13.6 Months) and doxycycline (11.6 Months) (p=0.532). Conclusion : with the use of OK-432, for pleurodesis, was as effective as doxycycline, can be considered as an alternative treatment for malignant effusion in patients with lung cancer.