Abstract: AIM To investigate the clinical efficacy and safety of ticagrelor and double dosage of clopidogrel in clopidogrel-resistant acute coronary syndrome (ACS) patients. METHODSOne hundred and twenty-four ACS patients with clopidogrel resistance (platelet inhibition rate <30%) were randomly divided into ticagrelor group (group A, n=63) and double dosage of clopidogrel group (group B, n=61). Platelet inhibition rate was tested at the seventh day after admission and high sensitivity C-reactive protein (hs-CRP) was measured at the second day and the seventh day after admission. The incidence rates of major adverse cardiovascular events (MACE) and slight bleeding were compared between groups at the first- and sixth-month follow-up. RESULTSAt the seventh day, platelet inhibition rates in the two groups were significantly elevated (P<0.05) and platelet inhibition in group A was higher than in group B (P<0.05). At the second day, no significant difference in hs-CRP was observed between groups. However, at the seventh day, the hs-CRP in the two groups was significantly reduced (P<0.05) and the hs-CRP in group A was lower than in group B (P<0.05). At the first-month follow-up, there was no significant difference in the incidence rates of MACE and slight bleeding between groups and at the 6-month follow-up, the incidence rate of MACE in group A was significantly lower than in group B (P<0.05), but there was still no significant difference in the incidence rate of slight bleeding between groups. CONCLUSIONTicagrelor is more effective and safer in the treatment of clopidogrel-resistant ACS patients.