['In recent years, importance of enzyme activity measurements, in addition to genotyping, in epidemiological studies relating paraoxonase 1 (PON1) and vascular disease was emphasized. This is the first report evaluating paraoxonase and arylesterase activities as risk factors for ischemic stroke. In addition, PON1 192Gln(Q)/Arg(R) and 55Leu(L)/Met(M) polymorphisms were also analyzed.', 'The study population was comprised of 108 ischemic stroke patients and 78 controls. Enzyme activities were determined by spectrophotometric assays and for genotyping, standard PCR protocols followed by restriction enzyme digestions were used.', 'The prevalence of the PON1 192RR genotype was increased among stroke patients (16.7%) as compared to controls (9.0%, P=0.129). Paraoxonase and arylesterase activities and PON1 activity ratio (paraoxonase/arylesterase) were found to be lower in patients than in controls. Logistic regression analysis revealed PON1 activity ratio (odds ratio, OR=0.697, 95% CI, 0.541 to 0.898, P=0.005), PON1 192RR genotype (OR=3.434, 95% CI, 1.159 to 10.178, P=0.026) and PON1 status (PON1 activity ratio combined with PON1 192RR genotype; OR=1.406, 95% CI, 1.038 to 1.905, P=0.028) as significant predictors of stroke.'] Are paraoxonase/arylesterase ratio , PON1 192Q/R polymorphism and PON1 status associated with increased risk of ischemic stroke?