Abstract: Objective: To investigate the diagnosis, treatment and prognosis of lung cancer in Multiple Primary Carcinoma (MPC). Methods: Among the 754 cases with lung cancer admitted from January 2000 to December 2004, 27 non-small cell lung cancer (NSCLC) patients with MPC were selected based on the Warran and Gates MPC diagnosis criteria. Diagnosis, treatment and prognosis of the patients were summarized. Results: In the 27 patients, 4 suffered synchronous and 23 suffered metachronous symptoms. The surgical resection rate was 77.85% (21/27) and the radical correction rate was 59% (16/27). The 1-year and 3-year survival rates after radical resection were 80% and 46.7%, respectively, compared to 33% and 11% after palliative resection. Conclusions: MPC should be suspected in patients with a past history of malignant cancer. MPC should especially be considered in those with a tumor-free survival time of more than 2 years or in patients who have synchronous or metachronous solitary nodules in different lung lobes, without a history of carcinoma or mediastinal or systemic metastasis. MPC must be differentiated from lung metastasis. Whenever primary lung cancer is diagnosed, radical resection should be the first course of treatment to realize the best prognosis.