Aim: 7-Ketocholesterol concentrations can be measured in a blood sample; however, the relationship between blood 7-ketocholesterol concentrations and atherosclerotic disease is not well-known. The aim of this study was to clarify the clinical significance of serum 7-ketocholesterol concentrations (s-7KCHO) in the progression of coronary atherosclerosis. Methods: One hundred and thirty-nine subjects with coronary artery disease (CAD, subjects with stable angina pectoris or acute myocardial infarction) and 43 subjects with normal coronary arteries were enrolled in the study. s-7KCHO was measured using gas chromatography mass spectrometry. Results: s-7KCHO was significantly higher in subjects with CAD than in those with normal coronary arteries (normal coronary artery: 19.0 11.3 ng/mL, CAD: 32.4 23.1 ng/mL, p 0.01). Furthermore, patients with multiple vessel disease had significantly higher s-7KCHO than those with single vessel disease. Multivariate analysis revealed that s-7KCHO was an independent variable for CAD (p 0.01). In CAD subjects, the presence of acute myocardial infarction, number of affected vessels, and high sensitive C-reactive protein concentrations strongly correlated with s-7KCHO (p 0.01, 0.05, 0.05, respectively). Conclusion: These results indicate that high s-7KCHO is closely associated with the progression of coronary atherosclerosis and inflammation.