Objective To analyze the change of cysteinyl leukotriene ( Cys-LTs) levels and 8-Isopros-tane (8-iso-PG) levels in the exhaled breath condensate (EBC) of asthmatic children from acute exacerbation to clinical remission, and investigate the role of the detection of Cys-LTs and 8-iso-PG in EBC in its severity and pathogenesis , and explore the relationship between the Cys-LTs and 8-iso-PG through measuring Cys-LTs levels and 8-iso-PG levels in the EBC of asthmatic children. Methods The outpatient or inpatient asthmatic children of the pediatrics and a group of healthy children were studied. All subjects′ EBC were collected by the R-Tube produced by American Respiratory Research. The concentration of Cys-LTs and 8-iso-PG in EBC were measured by enzyme-linked immunosorbent assay (ELISA), and compared among children in asthmatic exacerbation, asthmatic remission, and healthy condition. The relevance of their change would be explored at the same time. Results (1) Cys-LTs levels in EBC were higher in asthma exacerbation, compared to healthy controls (P<0. 05), while no significant difference were found between asthmatic remission and asthmatic exacerbation or healthy controls ( P>0. 05 ) . ( 2 ) 8-iso-PG levels was higher in asthmatic exacerbation compared to asth-matic remission ( P<0. 05 ) . Moreover, the 8-iso-PG levels were significantly higher in asthmatic remission than in healthy controls (P<0. 05). (3) Through the relevance analysis of the Cys-LTs and 8-iso-PG levels in EBC among the three groups, Cys-LTs levels in EBC of asthmatic exacerbation significantly were correlated with 8-iso-PG levels (n1 =35, r1 =0. 61, P<0. 05), while there was no significant correlation between 8-iso-PG levels and Cys-LTs levels in asthmatic remission. Conclusion The increase of 8-iso-PG levels in EBC of bronchial asthmatic patients correlates with the disease and its control. Therefore, 8-iso-PG can be an objective indicator for asthmatic diagnosis and healing efficacy. Cy-LTs levels increase in the EBC of bronchial asthmatic according to disease severity. The two levels correlate during asthmatic exacerbation, indicating that a link be-tween airway oxidative stress and inflammation among asthmatics.