Abstract: Abstract Background: We aimed to investigate whether changes occur in the subcarinal angle (SCA) in chronic obstructive pulmonary disease (COPD) and examine the effects of such changes on mortality rates. Materials and Methods: The study included 108 COPD patients; who were followed up in the intensive care unit (ICU) in the period between January 2018 and December 2018 and who had available posterior-anterior chest X-rays (PA-CXRs), APACHE-II (Acute Physiology and Chronic Health Evaluation-II) scores, and laboratory values in the electronic archiving system. SCA values on PA-CXRs were recorded in the Picture Archiving and Communication System (PACS). Patients were divided into two groups as survivors and nonsurvivors. Results: In our study; congestive heart failure, as one of the comorbid diseases with COPD, was found to be associated with mortality (p: 0.011). Furthermore; APACHE-II scores (p: 0.001), SCA values (p: 0.025), elevated CRP levels (p: 0.01), hypoalbuminemia (p: 0.018), and high creatinine values (p: 0.034) were associated with mortality. Conclusions: Our results are compatible with those of previous studies in the literature demonstrating that advanced age, elevated CRP levels, APACHE-II scores, hypoalbuminemia, and high creatinine values were all associated with mortality in COPD patients. Furthermore, SCA was found to be narrower in nonsurvivors in our study. We think that our study results will contribute to the literature because this is the first study that demonstrated the association between SCA and mortality in COPD patients.