Aims: This study aimed to determine the role of cardiothoracic ratio in predicting coronary atherosclerosis in young adult patients. Methods: In this single-center retrospective study, young adult patients who underwent coronary computed tomography angiography (CTA) with suspicion of coronary artery disease between October 2022 and May 2024 were included. Demographic and clinical histories of all patients were determined from the medical record system. Coronary artery calcium scores (CACSc) and cardiothoracic ratios (CTR) of the patients in question were calculated and recorded from the coronary CTA images. Result: A total of 264 young adult patients under the age of 45, with an average age of 42.2±3.1 years, were included in this study. The patients included in the study were divided into two groups according to the presence of atherosclerotic calcific plaque in coronary CTA. Smoking history, hyperlipidemia, hypertension and diabetes mellitus history were significantly different in the two patient groups (for all, p