Background: Primary percutaneous intervention (PCI) is the favored reperfusion strategy to achieve normal cardiac blood flow. Objective: To study if the level of NT-pro BNP before primary PCI can be used as an independent predictor for successful reperfusion in cases presented with STEMI after primary PCI. Patients and Methods: This study included 40 cases subjected to Emergency Departments of Ain Shams University and Misr University for Sciences and Technology (MUST) Hospitals from September 2021 to June 2022, diagnosed with STEMI and had been revascularized by primary PCI. Serum samples for NT-pro BNP were collected before primary PCI and correlated with the TIMI flow, MBG grades, and ST resolution post primary PCI. Results: Our study demonstrated a higher baseline NT-pro BNP level that was significantly correlated with increased risk of poor myocardial reperfusion following primary PCI expressed by ST resolution less than 50%, TIMI flow grade < 3 as well as MBG < 3 and was also associated with increased incidence of No Reflow. Conclusion: Initial NT-pro BNP level in STEMI cases correlates with myocardial reperfusion following primary PCI besides its early marker for risk stratification of STEMI patients. High-risk patients are in need of more aggressive complementary treatment strategies to improve microvascular perfusion and optimization of medical treatment.