Background: Chronic obstructive pulmonary disease (COPD) is a common comorbidity in lung cancer that can affect treatment options and patient outcomes. We aimed to investigate the prevalence and clinical characteristics of COPD in lung cancer patients in middle-income country. Material and methods: Retrospective cohort study of lung cancer patients referred to lung function testing at The Institute for Pulmonary Diseases of Vojvodina, Sremska Kamenica, Serbia, between January 2015. and January 2020. Results: There were 1086 patients, 713 males (65.6%), median age 65 years (IQR 60-70). Most common types of cancer were adenocarcinoma (n=448, 41.2%) and squamous cell carcinoma (n=442, 40.7%). COPD was present in 552/1086 (48.1%) of the patients, mostly GOLD stage 2 (264/552; 50.6%) and GOLD stage 1 (198/522; 37.9%). COPD was newly diagnosed in 330/522 (63.2%) of the patients. Compared to patients without COPD, COPD patients were more likely to be male (58.5% vs. 73.4%, p<0.001), older (63.1±9.2 vs. 65.8±7.0 years p<0.001), have more exposure to smoking (pack years, 42.8±28.4 vs. 50.1±27.1, p<0.001), lower lung function (FEV1% 95.2±18.9 vs. 72.9± 18.7, p<0.001, DLCO% 77.4±18.2 vs. 67.6±18.7, p<0.001), coronary artery disease (7.1% vs. 12.8%, p=0.002) and squamous cell carcinoma (37.6% vs. 44.1%, ±p=0.03). There was no difference in TNM stage and ECOG performance status.