Objective To evaluate the effect and safety of ticagrelor in the elderly patients with ST segment elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PCI). Methods Two hundred and forty consecutive elderly STEMI patients undergoing primary PCI in our hospital from November 2012 to December 2014 were recruited in this study, and divided into ticagrelor group (n=94) and clopidogrel group (n=146). Thrombolysis in myocardial infarction (TIMI) grade 3 flow, post-operative ST segment resolution (STR), bleeding incidence by Bleeding Academic Research Consortium (BARC) scale, dyspnea incidence, medication and causes for withdrawal and discontinuation of drugs, intra-hospital and 12-month occurrence of major adverse cardiac events (MACE) were observed and compared between the 2 groups. Results The percentage of TIMI grade 3 flow was significantly higher in the ticagrelor group than in the clopidogrel group (90.5％ vs 80.8％, P=0.024). But there were no significant differences in the incidences of BARC types and dyspnea between the 2 groups (28.7% vs 24.0%, P=0.412; 12.8% vs 6.8%, P=0.121). Compared with the clopidogrel group, there were more patients with drug withdrawal or discontinuation of antiplatelet therapy in the ticagrelor group in the 12 months’ follow-up (P<0.001). The withdrawals of ticagrelor or clopidogrel mainly attributed to doctor’s preference, cost and severe dyspnea (500% vs 14%, P<0001; 128% vs 14%, P<0.001; 5.3% vs 0.7%, P=0.025). No significant difference was found in the incidence of MACE between the 2 groups during hospital staying and 12 months’ follow-up (5.3% vs 5.5%, P=0.957; 8.5% vs 8.9%, P=0.916). Conclusion Ticagrelor significantly improves blood flow in the elderly patients with STEMI after primary PCI and has no effect on the incidence of BARC bleeding. The reasons for withdrawal and discontinuation of ticagrelor are doctor’s preference, cost and dyspnea.