Abstract: Objective To explore clinical features of multiple primary malignant neoplasms with lung cancer. Methods Retrospective analysis was performed on patients with multiple primary malignancies in all lung cancer patients admitted to the department of respiration of Chinese PLA General Hospital from January 2010 to May 2015. Clinical characteristics of multiple primary malignancies involving lung cancer was investigated. Results Of the 2 780 patients with lung cancer, 55 cases were multiple primary malignancies, accounting for 1.96%. Of the 55 cases, 53 cases had two malignancies and 2 cases had three malignancies. The male to female ratio was 40 to 15 (2.67∶1). Of the 55 patients in this study, 16 had lung cancer diagnosed ahead of other primary cancer (lung cancer group) and the remaining 39 patients had another cancer developed before lung cancer (control group). The mean age of patients was 62.81 years old in the lung cancer group and 63.15 years old in the control group. There was significant difference in the interval between first cancer and second cancer in the lung cancer group and the control group (mean 31.94 months vs 85.13 months, P＜ 0.05). The most frequent location of the other malignancies was gastrointestinal tract (36.36%), followed by urogenital region (27.27%). Regarding the histologic type of lung cancer, adenocarcinoma (49.09%) was the most common type. There was a high proportion of smoking patients (62.27%) with significant difference between two groups (87.5% vs 58.97%, P＜ 0.05). Conclusion Among the patients with multiple primary malignancies involving lung cancer, gastrointestinal tract cancer is the most common cancer accompanying lung cancer and adenocarcinoma is the most common histologic type of lung cancer. Smoking is a risk factor for the development of multiple primary neoplasms.