Background: The relationship between preprocedural C-reactive protein (CRP) levels and the incidence of contrast-induced acute kidney injury (CI-AKI) is unknown. Methods: Documents of 7,310 consecutive patients undergoing percutaneous coronary intervention (PCI) were screened. Patients with acute myocardial infarction, cardiogenic shock, concomitant inflammatory conditions or undergoing CABG within 48 h were excluded due to potential confounding effects. Results: A total of 4,522 patients were valid for analysis. The median follow-up was 26 months (interquartile range 20-33 months). According to preprocedural CRP values, patients were divided into 3 groups: group 1: CRP < 1.0 mg/l (n = 1,523); group 2: 1.0 mg/l <= CRP <= 3.0 mg/l (n = 1,626); group 3: CRP > 3.0 mg/l (n = 1,373). Patients with higher preprocedural CRP levels were associated with a significantly increased rate of CI-AKI (10.6 vs. 14.9 vs. 23.5%, p < 0.0001). After adjustment for baseline covariates, CRP level was still an independent predictor for the incidence of CI-AKI, either as a continuous variable or a categorical variable. Patients with higher CRP values had a significantly higher rate of all-cause mortality and myocardial infarction during follow-up. Conclusion: Elevated preprocedural CRP is associated with an increased risk for CI-AKI in patients undergoing PCI. Pre-procedural risk stratification with CRP as an adjunct to established clinical risk factors might be useful. Copyright (C) 2011 S. Karger AG, Basel