Abstract: Objective To analyze the clinical manifestation, diagnosis, treatment and prognosis of patients with combined idiopathic pulmonary fi brosis and lung cancer. Methods Clinical data about 21 patients with defined idiopathic pulmonary fi brosis and lung cancer (IPF-Ca), 21 patients with defined idiopathic pulmonary fi brosis and 21 patients with defined lung cancer admitted to Chinese PLA General Hospital from January 2003 to December 2013, were retrospectively analyzed. Results The mean survival time of patients with IPF-Ca was shorter than patients with IPF or lung cancer (12 months, 33 months, 17 months, P< 0.05). At the onset of the disease, patients with IPF-Ca (52.4%) had higher incidence of respiratory failure than patients with IPF (14.3%) (P< 0.05). Patients with IPF-Ca had higher carbon monoxide diffusion capacity (DLco) (54.9%±22.0%) than patients with IPF-Ca (39.0%±19.1%) (P< 0.05). Oldness (OR=4.06, 95% CI: 1.15 - 14.41, P=0.030 0) and smoking (OR=3.86, 95% CI: 1.00 - 14.89, P=0.049 5) were the primary risk factors of patients with IPF-Ca. On chest CT, 52.4% of lung cancers were inside the fi brotic area while 47.6% were outside the fibrotic area. The major pathological types were squamous carcinoma (47.6%), adenocarcinoma (38.1%), small cell lung cancer (9.5%) and large cell lung cancer (4.8%). Conclusion The mean survival time of patients with IPFCa is shorter than patients with IPF or lung cancer. The risk factors are oldness and smoking, and the major pathological types are squamous carcinoma and adenocarcinoma.