To determine the clinical efficacy, adverse events and side-effect dyspnea of and CYP3A5 expressor status in ticagrelor treated patients. Ticagrelor treated patients from the POPular Genetics randomized controlled trial were genotyped for and alleles. Patients were divided based on their genotype. In total 1,281 patients with ST-segment elevation myocardial infarction (STEMI) were included. carriers ( = 152) non-carrier status ( = 1,129) were not found to have a significant correlation with the primary thrombotic endpoint: cardiovascular death, myocardial infarction, definite stent thrombosis and stroke 1.3% vs. 2.5%, adjusted hazard ratio 1.81 (0.43-7.62) , or the primary bleeding endpoint: PLATO major and minor bleeding 13.2% vs. 11.3%, adjusted hazard ratio 0.93 (0.58-1.50) . Among the patients, CYP3A5 expressors ( = 196) non-expressors ( = 926) did not show a significant difference for the primary thrombotic 2.6% vs. 2.5%, adjusted hazard ratio 1.03 (0.39-2.71) , or the primary bleeding endpoint 12.8% vs. 10.9%, adjusted hazard ratio 1.13 (0.73-1.76) . With respect to dyspnea, no significant difference was observed between carriers non-carriers 44.0% vs. 45.0%, odds ratio 1.04 (0.45-2.42) , or in the group, CYP3A5 expressors CYP3A5 non-expressors 35.3% vs. 47.8%, odds ratio 0.60 (0.27-1.30) . In STEMI patients treated with ticagrelor, neither the carriers, nor the CYP3A5 expressor status had a statistical significant effect on thrombotic and bleeding event rates nor on dyspnea. ClinicalTrials.gov, identifier NCT01761786.