Elevated Low density lipoprotein (LDL) / High density lipoprotein (HDL) ratio is a risk factor for predicting coronary artery disease (CAD). Paraoxonase 1 (PON1) is a HDL associated serum enzyme. PON1 protects LDL from oxidative modifications and thus has a protective effect against CAD progression. There are two common polymorphisms, Q192R and L55M, in PON1 gene. There may be a relationship between these polymorphisms and CAD and/or elevated LDL/HDL ratio. Therefore, we decided to evaluate effect of these polymorphisms individuals not only with CAD compare with others without CAD but also, with high and normal LDL/HDL ratio. To evaluate Q192R and L55M polymorphisms, we choose 29 patients with recent myocardial infarction (case group) and 34 healthy volunteers without cardiac problems (control group). PCR was carried out using specific primers. Then, PCR products were digested by RFLP. Serum LDL and HDL levels were enzymatically detected. Genotype frequencies for L55M were determined: 17.2%LL, 27.6%LM, and 55.2% MM in case group but, 47.1%LL, 35.3%LM, and 17.6% MM in control group. On the other hand, frequencies of L55M polymorphism in those with high LDL/HDL were 22.5%LL, 35%LM, and 42.5%MM but, 52.2%LL, 26.1%LM, and 21.7%MM in those with low LDL/HDL ratio. Frequencies of Q192R polymorphism were not apparently with CAD or change in LDL/HDL ratio. Thus, L55M polymorphism may be an independent risk factor for cardiovascular disease. Since L55M polymorphism was associated with familial history of cardiovascular disease, it is better to evaluate L55M polymorphism in younger ages even in the absence of high LDL/HDL ratios.