The purpose of the present study was to retrospectively analyze the clinicopathological characteristics and clarify the validity of surgical resection for patients with positive pleural lavage cytology (PLC). Between 1993 and 2006, 563 patients who underwent complete surgical resection for primary non-small cell lung cancer and who were examined with regard to PLC were retrospectively analyzed. Forty-two patients (7.2%) showed positive PLC. The 5-year survival rates were 65.0% and 33.5% for patients with negative and positive PLC, respectively. The 5-year survival rates for patients with positive PLC were 57.1%, 50.8%, 40.0%, and 0% for pathological stage I, II, IIIA, and IIIB, respectively. Multivariate analysis revealed that preoperative carcinoembryonic antigen (CEA) level, PLC, vascular invasion, lymphatic permeation, and pathological stage were independent prognostic factors. The 5-year survival rate for the patients with a high CEA level and positive PLC was 0%. Intrathoracic recurrence was observed more frequently in patients with positive PLC. PLC was an independent prognostic factor. While positive PLC alone may not be a contraindication for surgical resection, patients who are complicated with a high CEA level preoperatively should receive special attention since no long-term survivors were observed.