A total of 184 patients with small cell lung cancer (SCLC) including 18 patients with ipsilateral pleural effusion as the only evidence of metastasis beyond the primary tumor site (PL), 84 patients with limited disease (LD), and 82 patients with extensive disease (ED) were treated at the Osaka Prefectural Habikino Hospital between December 1982 and June 1990. The median survival time for patients with PL was 51 weeks; for the patients with LD, 51 weeks; and for the patients with ED, 34 weeks. The survival of PL patients was significantly better than that of ED patients (P less than 0.05), and did not differ from that of LD patients. The response rate of PL patients was not significantly different from the response rates observed in LD- and ED-patients. There was no significant difference in survival or response rate between patients with cytologically positive and those with cytologically negative PL. Ipsilateral pleural effusion was not found to be a independent prognostic factor for survival from multivariate analysis in LD patients. These results indicate that the classification of limited disease small cell lung cancer should include patients with ipsilateral pleural effusion, as suggested by the consensus report at the International Association for the Study of Lung Cancer (IASLC) Workshop in 1989.