["To evaluate paraoxonase1 (PON1) activities and malondialdehyde (MDA) levels, one of the end products of lipid peroxidation induced by reactive oxygen species in patients with Behçet's disease (BD) in the active stage.", 'Serum MDA levels and PON1 levels were measured spectrophotometrically in 16 patients with BD in the active stage of the disease and in 15 healthy subjects who constituted the control group.', 'In the BD group, median (range) serum PON1 and MDA levels were 149.64 U/l (88.02-281.68) and 1.21 nmol/ml (0.90-3.42), respectively. In the control group, median (range) serum PON1 and MDA levels were 206.86 U/l (114.43-422.52) and 0.72 nmol/ml (0.50-1.12), respectively. There was a statistically significant decrease in serum PON1 levels (p = 0.02) and an increase in serum MDA levels (p<0.001) in patients with BD in the active stage when compared to controls.'] Is serum paraoxonase activity decreased in the active stage of Behçet 's disease?