Abstract: Objective To investigate the effects of atorvastatin combined with ezetimibe on serum cholesterol synthesis and absorption in acute coronary syndrome patients not achieving LDL-C goal. Methods Eighty ACS patients not achieving LDL-C goal in our hospital from June 2012 to June 2014 were randomly divided into atorvastatin plus ezetimibe group (n=42, atorvastatin 20 mg/d plus ezetimibe 10 mg /d) and atorvastatin double-dose group (n=38, atorvastatin 40 mg/d). Serum cholesterol synthesis and absorption markers were measured before and after 12-week treatment. Results After 12 weeks, the serum LDL-C level was significantly lower in atorvastatin plus ezetimibe group than that in double dose atorvastatin group (1.81±0.38) mmol/L vs (2.01±0.43) mmol/L, P＜ 0.05. Serum cholesterol synthesis markers (lathosterol, 24-dehydrogenation) decreased after 12-week treatment in the two groups, particularly in double dose atorvastatin group. Cholesterol absorption markers (campesterol, stigmasterol, sitosterol) decreased in atorvastatin plus ezetimibe group after 12-week treatment (P＜ 0.05, respectively). However, they increased in the double dose atorvastatin group. Conclusion Atorvastatin combined with ezetimibe reduce cholesterol synthesis and absorption markers at the same time in acute coronary syndrome patients not achieving LDL-C goal.