Objective To investigate levels of 8-isoprostane in serum of patients with bronchial asthma. Methods Eighteen patients diagnosed with acute exacerbation of asthma were enrolled as the experimental group from Department of Respiratory Medicine from February 2009 to August 2009. After treatment all the patients reached remission. Twenty healthy workers from Department of Respiratory Medicine were enrolled as the control group in August 2009. The levels of 8-isoprostane in serum of all subjects were measured, and their FEV1% pred was also evaluated. Results The levels of 8-isoprostane in serum were significantly higher in patients with acute exacerbation of asthma compared with those in remission stage and the healthy control group [ ( 157. 46 ±46. 99) pg/mL vs. ( 43. 52 ±13. 62) pg/mL and( 15. 23 ±1. 96) pg/mL, P lt;0. 01] . Meanwhile the levels of 8-isoprostane in serum of patients with asthma in remission stage were significantly higher compared with the healthy control group ( P lt;0. 05) . The levels of 8-isoprostane in serum were negatively correlated with FEV1% pred in the asthma group( r = - 0. 533,P lt;0. 05) . Conclusions 8-isoprostane as amarker of oxidative stress response involves in the pathogenesis of asthma. Monitoring 8-isoprostane levels in serum may reflect the state of oxidative stress, and may be useful for severity judgment and follow-up of treatment effectiveness in patients with asthma.