Background: Coronary artery ectasia (CAE) is a well-recognised disorder characterised by abnormal dilation of the coronary arteries. Underlying mechanisms associated with abnormal luminal dilation in CAE remain to be elucidated. However, histopathological features resemble those of coronary atherosclerosis. Galectin-3 (Gal-3) is a valuable biomarker for both progression and destabilisation of atherosclerotic lesions. To the best of our knowledge, there is no study in the literature examining serum Gal-3 levels in patients with isolated CAE. In the present study, therefore, we aimed to investigate the possible relationship between serum Gal-3 levels and isolated CAE.