Bile acids play important roles in lipid metabolism. Several studies have found that patients with coronary artery disease (CAD) have lower bile acid fecal excretion compared to individuals without CAD. However, few studies have focused on the roles of more accessible serum total bile acids (TBA) in the progression of CAD. The aim of this study was to explore the potential relationship between fasting serum TBA and the presence of CAD, myocardial infarction (MI) and severity of coronary lesions. A total of 7438 consecutive patients with suspected CAD, who had undergone coronary angiography, were enrolled. The severity of coronary lesions was evaluated using the Gensini score (GS). The relationships between fasting serum TBA and the presence and severity of CAD were evaluated. CAD patients had lower serum TBA than individuals without CAD, and patients with MI had lower TBA than those without CAD. Spline analyses showed an L-shaped relationship of the fasting serum TBA with the presence and severity of CAD, and the breakpoint approximated the normal upper limit (10 μmol/L). A lower TBA concentration (less than the median 3.6 μmol/L) was independently and significantly associated with the presence and severity of CAD, especially for the presence of MI (odds ratios 2.04, 95% confidence interval (1.71-2.44), C-index 0.9269). Fasting serum TBA level is highly associated with the presence and severity of CAD in patients undergoing coronary angiography for suspected CAD. Copyright © 2019 Elsevier B.V. All rights reserved.