The aim of this study was to investigate serum paraoxonase (PON) activity, total antioxidant capacity and serum level of lipid peroxidation products in children with exacerbated bronchial asthma. The study was performed in 23 children (17 males and 6 females, age 3-17 years) admitted to the hospital with asthma exacerbation. Aliquots of serum were collected before administration of any treatment. Control group comprised of 22 children (11 males, 11 females, age 3-17 years) admitted to the Department of Orthopedics for planned surgery, none of them demonstrated symptoms of asthma or other allergic diseases. Paraoxonase activity demonstrated right-skewed distribution both in control and in experimental group. The mean PON activity was 15% lower in asthmatic group but the difference was not significant. Total antioxidant potential of assayed sera as ferric reducing ability was significantly decreased in the group with asthma (-23.8%) and near-significantly correlated with number of days of hospitalization (r = -0.42; p = 0.07). The concentration of thiobarbituric acid-reactive substances (TBARS), a marker of lipid peroxidation, was 115.3% higher in asthmatic than in control group. TBARS correlated positively with eosinophils count in peripheral blood (r = 0.49; p < 0.01) and negatively with antioxidant capacity (r = -0.53, p < 0.05). We conclude that serum concentration of lipid peroxidation products is increased in children with bronchial asthma exacerbation. Total antioxidant capacity of serum is depressed during exacerbation of asthma. Serum paraoxonase activity tends to decrease in children during exacerbation of bronchial asthma, but the difference is not significant.