The LL genotype among subjects with paraoxonase (PON) polymorphism Met-Leu 54 has been shown to be associated with elevated risk of coronary heart disease. Indeed, insulin resistance (IR) is a well known cardiovascular risk factor that is likely attributable to a genetic background, lifestyle, and environmental factors such oxidative stress. Because subjects sharing the LL genotype have a more elevated degree of oxidative stress, one cannot rule out that in those subjects a more severe degree of IR can occur. Thus, the possible relationship between PON gene polymorphism and degree of IR was investigated. In 213 healthy subjects, the degree of IR was assessed by the homeostasis model assessment, and the Met-Leu 54 PON polymorphism was detected. The frequency was 0.366 for the LL genotype, 0.469 for the LM genotype, and 0.164 for the MM genotype. Comparing the three genotype groups, LL genotype had the more severe degree of IR, compared with LM (P < 0.01) and MM (P < 0.01) genotypes. No difference between LM and MM genotypes was found (P = 0.49). Subjects carrying the LL genotype were associated with the IR syndrome picture more than individuals carrying the M allele because they were more overweight and had the highest levels of triglycerides and blood pressure and the lowest values of plasma high-density lipoprotein cholesterol. In a multivariate stepwise regression analysis, LL genotype was a significant predictor of IR, independent of age, sex, body mass index, fasting plasma triglycerides, and high-density lipoprotein cholesterol (P < 0.001). In conclusion, the presence of LL PON genotype is associated with a more severe degree of IR. Thus, IR might be the possible missing link between Met-Leu 54 PON polymorphism and the increased cardiovascular risk.