['Human serum paraoxonase-1 (PON1) protects lipoproteins against oxidation by hydrolysing lipid peroxides in oxidized low-density lipoprotein, therefore it may protect against atherosclerosis. One of the two common PON1 gene polymorphisms within the PON1 gene is the Q192R, whose prevalence can be estimated by phenotype distribution analysis. The goal of this study was to clarify the role of PON1 phenotypes on the effect of three different statins on paraoxonase activity and lipid parameters.', 'One hundred and sixty-four patients with type IIb hypercholesterolaemia were involved in the study. We examined the effect of 10 mg day(-1) atorvastatin, 10/20 mg day(-1) simvastatin and 80 mg day(-1) extended-release fluvastatin treatment on lipid levels and paraoxonase activity in patients with different PON1 phenotypes. The phenotype distribution of PON1 was determined by the dual substrate method.', 'Three months of statin treatment significantly increased paraoxonase activity in every statin-treated group. In patients with AB+BB phenotype, statin treatment was significantly more effective on paraoxonase activity than in the AA group. Statin treatment more effectively decreased triglyceride levels in the AB+BB group compared with the AA group in the whole study population and in the simvastatin-treated group. Atorvastatin treatment was significantly more effective on apolipoprotein B levels in patients with AB+BB phenotype than in the AA phenotype group.'] Does the human paraoxonase-1 phenotype modify the effect of statins on paraoxonase activity and lipid parameters?