Background: no reflow phenomenon is associated with major adverse cardiac events, prediction of no reflow using laboratory and noninvasive imaging techniques can help in early prevention and management of this phenomenon. Objectives: to investigate the predictive value of serum sP-selectin and endothelial dysfunction assessed by using brachial artery flow mediated dilation (FMD)  in patients with STEMI undergoing primary PCI to address patients with high incidence of no reflow. Methods: the prognostic performance, clinical and angiographic correlates of sP-selectin and FMD was assessed in 96 patients admitted in National Heart Institute and Ain Shams University Hospitals by STEMI and underwent primary PCI as a reperfusion strategy. Each patient was subjected to (history taking, clinical examination, laboratory investigations including withdrawal of serum samples for detection of sP-selectin levels, echocardio-graphy, assessment of endothelial dysfunction by measuring the FMD, assessment of the angiographic results using TIMI flow grade and myocardial blush grade. Follow up of the patients during hospital stay and after one month for the incidence of MACE. Results: a significant correlation between patients with high serum sP-selectin and TIMI flow ≤ II was found (P=0.038) and between the serum levels of the sP-selectin and the MBG score (P=0.009), also a significant correlation between the FMD and the MBG score among the study cases (P=0.029) as well as a significant correlation between the FMD and the serum P-selectin level among study cases (P=0.016). There were no statistical significance between TIMI flow grade and brachial artery FMD (P=0.075). Also no significant correlation was found  between the patients' serum levels of sP-selectin, brachial artery FMD  and the incidence of MACE during the hospital stay or during one month of follow up after discharge (P=0.127 and P=0.693, respectively). Conclusions: serum sP-selectin level in patients with STEMI treated by primary PCI can predict the patients who will develop no reflow phenomenon after PCI, FMD could not predict the incidence of no reflow among those patients.