Background: The effects of high-sensitivity C-reactive protein (hs-CRP) levels on clinical outcomes in chronic-phase acute coronary syndrome (ACS) patients undergoing aggressive lipid-lowering therapy remain unclear. We examined the effects of hs-CRP levels on the prognosis of ACS patients who underwent aggressive lipid-lowering therapy and determined treatment targets for hs-CRP value. Methods: This post-hoc sub-analysis of a prospective randomized control trial (HIJ-PROPER) included 1734 ACS patients with dyslipidemia, who were divided into hs-CRP quartiles after 3 months of treatment. Primary endpoints were combined all-cause death, non-fatal myocardial infarction, non-fatal stroke, unstable angina, and ischemia-driven coronary revascularization. Secondary endpoint was allcause death. Results: The median follow-up period was 3.7 years. Overall, 1415 patients were evaluated retrospectively. No significant among-group differences were noted in low-density lipoprotein cholesterol (LDL-C) levels over time (p = 0.44). Kaplan-Meier analyses revealed that the incidence of the primary and secondary endpoints was significantly higher in the highest hs-CRP group than in the other groups [hazard ratio (HR) = 1.52, 95% confidence interval (CI) = 1.16-2.00, p < 0.01; HR = 5.30, 95% CI = 2.47-11.32, p < 0.01, respectively]. The cut-off hs-CRP level to predict all-cause death was 0.74 mg/L (receiver operating characteristic curve: sensitivity: 68%, specificity: 62%). Multivariate analyses revealed that hs-CRP >= 0.74 mg/Lat 3 months was correlated with an increased risk of all-cause death (adjusted HR = 3.68, 95% CI = 2.22-6.10, p < 0.01). Conclusion: Elevated hs-CRP levels independently predicted a worse prognosis, regardless of LDL-C levels, suggesting that interventions against elevated inflammatory responses plus intensive lipidlowering therapy and coronary revascularization are encouraging options for secondary prevention in ACS patients. (C) 2019 Japanese College of Cardiology. Published by Elsevier Ltd. All rights reserved.