Isolated coronary artery ectasia (ICAE) is defined as the ectasia of the coronary arteries without concomitant coronary artery stenosis. The etiology and the clinical course of ICAE are still not clear. Increased levels of plasminogen activator inhibitor-1 (PAI-1) inhibit vasa vasorum, leading to diminished vessel wall supply and thus contributes to aortic aneurysm expansion. Whether the same process has role in coronary artery ectasia is not known. The aim of this study is to investigate the association between PAI-1 and coronary artery ectasia in patients without concomitant obstructive coronary artery disease. Among 2830 patients who underwent coronary angiography between March 2010 and 2011, 55 patients (40 male, 15 female, mean age 60 ± 8 years) with ICAE, formed our study group. 27 patients with similar patient characteristics, with angiographically proven normal coronary arteries, were enrolled as the control group. The basal characteristics were similar between two groups. PAI-1 levels were statistically higher in the ICAE group compared to the control group (104.13 ± 56.65 and 63.39 ± 35.01 ng/dl, respectively) (P = 0.008). A significant positive correlation between CAE and PAI-1 (r = 0.358, P = 0.007) was also demonstrated. Serum high sensitive C reactive protein (hsCRP) levels did not differ between two groups (P > 0.05). The plasma PAI-1 levels were significantly higher in ICAE patients compared to normal coronary artery group. Increased PAI-1 levels may diminish vasa vasorum by antiangiogenic activity leading to coronary ectasia.