Several studies showed that the survival rate of stage IIIB disease with malignant pleural effusion is worse than stage IIIB disease without malignant effusion. But, malignant pleural effusion was considered T4. To analyze changes the survival time for malignant pleural effusion, in the seventh revision of TNM classification for lung cancer. The records of all patients had to have either a histological or cytological diagnosis of non-small cell lung cancer (NSCLC), who were admitted to Wonkwang university hospital between January 2004 and December 2006 were reviewed retrospectively. We evaluated the survival time of 187 patients with advanced lung cancer with and without malignant pleural effusion. This included the pleural effusion or nodule M1 a (pleural dissemination, currently classified as T4), nodule(s) in the other lung M1 a (contralateral lung nodule, currently classified as M1), nodule(s) with the same lobe as the primary tumor T3 (currently classified as T4), other T4 factors T4 (T4 MO anyN), and extrathoracic sites of disease M1b (distant metastasis, currently classified M1). Among the 187 patients, T4anyNMO was 57 patients in the current TNM classification. In the next edition of the TNM classification, T4MOanyN-T4 (excluding same lobe nodules) was 12 patients, pleural dissemiantion-M1a was 45 patients, contralateral lung nodule(s)-M1a was 7 patients, and metastatic disease-M1b was 55 patients. We compared the survival time for these groups. Survival time was 11 months, 8 months, 11 months, and 4 months. The survival time of malignant pleural effusion was shorter than other T4 factors without pleural effusion. But, there was no remarkable difference in statistics due to small cases (p=0.23). We strongly suggest that malignant pleural effusion in advanced NSCLC will be categorized with metastatic disease.