Although cigarette smoking is known to be an important risk factor for renal disease, the mechanism by which smoking induces progressive renal disease in a healthy population has not been established. We hypothesized that oxidative stress (measured as 8-iso-prostaglandin F(2α), 8-iso-PGF2a), inflammation (highly sensitive C-reactive protein (CRP), hs-CRP) and nitric oxide may be associated with an alteration in the estimated glomerular filtration rate (eGFR) and proteinuria in otherwise healthy smokers. A total of 649 eligible subjects were classified according to their smoking status. Plasma NOx was measured using ozone-based chemiluminescence, urinary 8-iso-PGF2a was measured using enzyme immunoassay and serum hs-CRP was measured using a latex aggregation nephelometry method. The levels of 8-iso-PGF2a and hs-CRP increased in current smokers (P=0.001 and P=0.029, respectively), although there was not an increase in the NOx level. The prevalence of a high eGFR increased in light smokers (odds ratio (OR) 1.15 (95% confidence interval (CI), 0.61-2.17)) and heavy smokers (OR 2.33 (95% CI, 1.06-5.10)) when compared with non- and past smokers (P for trend=0.024). The multivariable-adjusted mean values of the eGFR in current smokers, reported from the lowest to the highest quintiles of hs-CRP levels, were 82.1, 85.1, 86.4 and 88.5 ml per min per 1.73 m² (P for trend=0.027). The mean values of proteinuria were 28.6, 34.6, 37.2 and 39.5 mg g⁻¹ creatinine (P for trend=0.003). The correlation coefficient between hs-CRP and eGFR was increased significantly (P=0.03) across non- (r=0.03), past (r=-0.17), light (r=0.13) and heavy smokers (r=0.31). In conclusion, cigarette smoking is a risk factor for renal function alteration in healthy smokers and is characterized by a high eGFR and a high urinary protein associated with an increase in the hs-CRP. This finding suggests that hs-CRP may help mediate the alteration of renal function in smokers.