Abstract: AIM To evaluate the long-term efficacy and safety of half-dose ticagrelor in elderly patients(>75 years) with acute coronary syndrome(ACS) combined with chronic renal insufficiency(CRI) in China. METHODS Ninety-three patients with ACS combined with CRI were randomly divided into full-dose ticagrelor group, loading dose of 180 mg followed by 90 mg bid(n=48) and half-dose ticagrelor group, loading dose of 90 mg, then 45 mg bid(n=45). Patients were recorded and followed for 12 months and the incidence of major adverse cardiac events, bleeding events and adverse reactions were compared between groups. RESULTS No significant difference was noted in baseline between groups except the prevalence rate of diabetes and the incidence rate of STE-ACS(P<0.05). During the 12-month follow-up, there were nine cases of major adverse cardiac events in full-dose group and six cases in half-dose group, with no significant statistical difference between groups(19% vs. 13%). There were 16 mild cases of bleeding events in the full-dose group and eight cases in the half-dose group. The percentage in half-dose group was significantly lower(13% vs. 33%, P<0.05) and there were no serious or fatal bleeding events in either group. There were 12 case of dyspnea in the full-dose group and nine cases in the half-dose group, with no significant statistical difference between groups(25% vs. 22%). Dyspnea in both groups was mild, tolerable and temporary. CONCLUSION Half-dose ticagrelor achieves the same efficacy as full-dose ticagrelor but half-dose ticagrelor is safer for elderly patients(>75 years) with ACS combined with CRI.