Background: Current guidelines recommended intensive low-density lipoprotein cholesterol lowering with statins, aiming at the target of 70 mg/dL (1.81 mmol/L) of low-density lipoprotein cholesterol for those with very high risk of coronary artery events. However, there is no multicenter study assessing the effect of intensive lipid lowering therapy with statins on acute coronary syndrome (ACS) in Chinese population. Methods: An open-label multicenter study is planned to evaluate whether intensive treatment with statins for 2 to 5 years results in more reduction of cardiovascular events in patients with ACS compared to the standard statin therapy. A total of 1,600 patients will be randomly assigned to receive intensive statin therapy (atorvastatin, 20 or 40 mg/d, or equivalent dose of other statins) or standard statin therapy (atorvastatin, 10 mg/d, or equivalent dose of other statins). Both groups will receive dietary counseling. Over the follow-up period, the primary outcome measure is the time to occurrence of cardiac death, nonfatal acute myocardial infarction, revascularization with either percutaneous coronary intervention or coronary-artery bypass grafting, documented unstable angina or severe heart failure requiring emergency hospitalization, and stroke. The planned duration for enrollment is between December 2006 and December 2009. Conclusions: The CHILLAS study will be the first multicenter study in a Chinese population using a patient-level analysis to compare the effects and safety of intensive statin therapy with that of standard-dose statin therapy, which may provide new evidence and therapeutic standards for the treatment of ACS. © 2009 Mosby, Inc. All rights reserved.