We sought to evaluate the impact of C-reactive protein (CHP) levels on in-stent restenosis after percutaneous coronary intervention. The plasma level of CRP is considered a risk predictor for cardiovascular diseases. However, the relationship between CRP and in-stent restenosis has been a matter of controversy Meta-analysis reduces variability and better evaluates the correlation. We performed a systemic search for literature published in March 2008 and earlier using MEDLINE (R), the Cochrane clinical trials database, and EMBASE (R). We also scanned relevant reference lists and hand-searched all review articles or abstracts from conference reports oil this topic. Of the 245 studies that we initially searched, we chose 9 prospective observational studies (1, 062 patients). Overall, CRP concentration was higher in patients who experienced in-stent restenosis. The weighted mean difference in CRP levels between the patients with in-stent restenosis and those without was 1.67, and the Z-score for overall effect was 2.12 (P=0.03). Our subgroup analysis that compared patients with stable and unstable angina showed a weighted mean difference in the CHP levels of 2.22 between the patients with and without in-stent restenosis, and the Z-score for overall effect was 2.23 (P=0.03) in 5 studies of unstable-angina patients. There was no significance in 4 Studies of stable-angina patients. In spite of significant heterogeneity across the studies, out meta-analysis suggests that preprocedurally elevated levels of CRP are associated with greater in-stent restenosis after stenting and that this impact appears more prominent in unstable-angina patients. (Tex Heart Inst J 2010;37(1):49-57)