Objective: Thrombolysis in Myocardial Infarction (TIMI) flow in ST-Elevation Myocardial Infarction (STEMI) is a prognostic predictor that is directly influenced by duration of culprit artery occlusion; ischemic time. It is unknown whether platelet reactivity measured by P2Y12 reaction unit (PRU) is affected by ischemic time or predictive of TIMI flow. Our objectives were to examine the effect of baseline PRU on TIMI flow and on ischemic time. Methods: Between May 2014 and August 2016, the study included 144 patients between four sites undergoing percutaneous coronary intervention (PCI) within 24 hours of tenecteplase, aspirin and clopidogrel for STEMI. The VerifyNow ® Assay measured baseline PRU prior to angiography. Ischemic time was defined as the duration between index symptom onset and tenecteplase administration. Kruskal-Wallis H test was conducted because the assumption of normality was violated to test differences in baseline PRU based on TIMI flow and based on time intervals prior to PCI. Results: Median ischemic time was 172 minutes (IQR 115-285). Baseline PRU did not differ based on TIMI flow grade {χ 2 (3)=3.00, p=0.39}. Baseline PRU was not affected based on ischemic time {χ 2 (3)=1.50, p=0.68)}. Conclusion: Platelet reactivity measured by PRU is not associated with TIMI flow or ischemic time. Future research is warranted to examine the association between baseline PRU and prognosis.