OBJECTIVE: Heredity plays an important role in the predisposition to atherosclerotic coronary artery disease (CAD), and its thrombotic complications. Paraoxonase, a high-density lipoprotein-associated enzyme capable of hydrolyzing lipid peroxides, is presumed to contribute to atherosclerosis and CAD. This study investigates the role of human paraoxonase 1 (PON 1) gene (Q192R) polymorphism in CAD risk among Chinese type 2 diabetic cases. DESIGN: A population-based case-control study of paraoxonase 1 gene (Q192R) polymorphism and the risk of CAD in Chinese type 2 diabetics. METHODS: Subjects included 201 angiographically documented CAD patients with type 2 diabetes and 231 control subjects with type 2 diabetes alone living in central China. Single strand conformational polymorphism (SSCP) analysis was used to screen for PON 1 gene (Q192R) polymorphism. RESULTS: Frequency of the R allele was 21.5% in the CAD patients and 12.0% in the control subjects. The presence of the R allele was significantly associated with risk of CAD (odds ratio (OR)=1.97; 95% confidence interval (CI)=1.36--2.86). CONCLUSION: Frequency of the 192R allele of the human paraoxonase 1 gene may be an independent risk factor for CAD in the Chinese type 2 diabetics studied.