Abstract： Objective To study the relationship between the level of LTC4,8-lsoprostane in exhaled breath condensate and the serious condition of patients with asthma.Methods 30 patients with asthma were enrolled in this study,16 cases were chronic persistent and 14 cases were clinical relieve.EBC was collected in all subjects with a self-designed experimental device.The concentrations of LTC4 and 8-Isoprostane in EBC were measured by enzyme immunoassay.Results Both LTC4 [ ( 67.38 ± 10.30) ng/ml,(41.21 ± 11.41 ) ng/ml ] and 8-Isoprostane levels[ ( 14.29 ± 10.74) ng/ml,( 12.40 ± 7.45 ) ng/ml ]were significantly increased in the asthma patients compared with the control subjects[ (17.15 ±7.48 )ng/ml,P ＜0.01 ].Exhaled LTC4 levels were obviously increased in the patients with chronic persistent asthma compared with those clinical relieve asthma,while 8-Isoprostane level had no significant difference between two asthma groups ( P ＞ 0.05 ).Conclusions Airway inflammation were persistent in asthma patients.LTC4 and 8-Isoprostane levels in EBC were associated with the serious condition of asthma,which indicated inflammation indicators might be useful in monitoring serious condition and guiding treatment for asthma patients.