Abstract Background Primary PCI is considered to be the preferred reperfusion strategy for STEMI. The goal of reperfusion is to resume normal blood flow to the cardiac tissues, and not just to achieve an open epicardial artery. Aim of the work The aim of this study was to evaluate the predictive value of NT-pro BNP before primary PCI in patients presenting with STEMI, for myocardial reperfusion assessed by the degree of ST resolution in the ECG 90 minutes post primary PCI, the TIMI flow and the MBG post primary PCI. Patients and Methods This study included 40 patients who presented to emergency departments of Ain Shams University hospitals and Misr University for Sciences and Technology hospital from September 2021 till June 2022, diagnosed with STEMI and had been revascularized by primary PCI as per the recommendations of The European society of cardiology guidelines for diagnosis and management of ST elevation myocardial infarction published in 2017. Serum samples for NT-pro BNP level were obtained before primary PCI to be correlated with the TIMI flow grade, the MBG, and the ST resolution post primary PCI. Results Our study had demonstrated that a higher baseline NT-pro BNP level is significantly associated with higher risk of poor myocardial reperfusion following primary PCI expressed by ST resolution less than 50%, TIMI flow grade less than 3 as well as MBG less than 3 and was also associated with higher incidence of No Reflow. Conclusion Initial NT-pro BNP level in STEMI patients correlates with myocardial reperfusion following primary PCI. This supports the potential use of NT-pro BNP as an early marker for risk stratification of patients with STEMI. High risk patients will be in need of more aggressive complementary treatment strategies to improve microvascular perfusion and optimization of the medical therapies to help decrease the development of heart failure.