The current study demonstrates that a disintegrin and metalloproteinase with thrombospondin type 1 motif- (ADAMTS-) 5 is a key extracellular matrix protease and associated with cardiovascular diseases. However, the plasma ADAMTS-5 levels and relevance of coronary artery disease (CAD) remain largely unknown. This study is aimed at examining the relationship between the plasma ADAMTS-5 levels and the severity of coronary stenosis in patients with CAD. In the present study, the expression of ADAMTS-5 was analyzed in coronary artery samples and blood. The results showed that the plasma ADAMTS-5 levels were lower in the CAD group than in the control group. In addition, significantly higher matrix metalloproteinase- (MMP-) 2 and MMP-9 levels were also observed in the patients with CAD, and the ADAMTS-5 levels were negatively correlated with the MMP-2 and MMP-9 levels. Spearman's correlation analysis showed that the Gensini score was negatively correlated with the ADAMTS-5 levels but was positively correlated with the MMP-2 and MMP-9 levels. Receiver-operating characteristic (ROC) analysis revealed that ADAMTS-5, MMP-2, and MMP-9 may have a certain diagnostic value in CAD and that the combination of all three metalloproteinases had a higher diagnostic value. The findings provided a better understanding of the role of ADAMTS-5 in the diagnosis of CAD.