Chronic obstructive pulmonary disease (COPD) patients have increased neutrophils and macrophages in their lungs, and inflammation of the airway is related to oxidative stress. This study assessed the levels of 8-isoprostane (an oxidative stress marker) and chemokines related to neutrophil and monocyte inflammation (growth-related oncogene alpha [GROalpha] and monocyte chemoattractant protein-1 [MCP-1]) in the airway of ex-smoking COPD patients by exhaled breath condensate (EBC) collection. Thirty-two (28 males) stable COPD patients (14 with FEV(1) 50% [Group 1], 18 with FEV(1) <50% predicted [Group 2]) and 18 non-smoking age and sex-matched controls were studied in this cross-sectional study. EBC was collected using the EcoScreen (Jaeger, Germany) during 10 min of tidal breathing with the nose clipped. Concentrations of 8-isoprostane, GROalpha and MCP-1 were measured by enzyme immunoassays. COPD patients had a higher concentration of 8-isoprostane than controls (COPD versus control, P<0.001; Group 1 versus Group 2, P=0.045). 8-isoprostane increased across the groups from normal, Group 1 to Group 2 (r=0.64, P<0.001). The median intraquartile range (IQR) levels in pg/ml for GROalpha were 45.3(44.5-46.5), 45.4(44.5-46.0), 46.0(45.6-47.3), whereas MCP-1 levels were 5.3(5.2-5.9), 6.2(5.4-6.9) and 5.7(5.5-6.4) in Group 1, Group 2 COPD and control subjects, respectively. GROalpha level was lower in COPD patients when compared to controls (P=0.01). MCP-1 level did not differ between COPD and the control group. 8-isoprostane level, but not GROalpha and MCP-1, in EBC was increased in COPD patients with poorer lung function. This suggests an increased oxidative stress in the airway in patients with more severe COPD.