Acute coronary syndrome is a medical emergency. Its clinical presentations as ST elevation myocardial infarction (MI), non-ST elevation MI, or unstable angina, are related with high mortality. Evidence-based medicine showed lipid lowering effects by statins use can reduce cardiovascular events in primary and secondary clinical trial data. But the timing of statins in acute coronary syndrome was still arguable. It was unknown if early use of statin improved prognosis in acute coronary syndrome. This review focused on the recent evidences on the issues of statins use in acute coronary syndrome, including observational data and clinical trial data.