The aim of this study is to analyze the relationship between MPV on admission and left ventricular function in anterior STEMI patients undergoing primary PCI. MPV is a parameter showing platelet activation and function. MPV is a strong, independent predictor for angiographic reperfusion and in-hospital mortality in patients underwent primary PTCA. A total of 50 anterior STEMI patients who underwent successful primary PCI were included in this prospective cohort study conducted between January 2016 and December 2016. For all patients, admission MPV was recorded and transthoracic echocardiography was done before discharge. The patients were subdivided according to EF into 2 subgroups: Group (I): 26 patients with EF ≥ 50%. Group (II): 24 patients with EF < 50%. There was a significant statistical difference between the two groups regarding the left ventricular function by Echo (p value = 0.002). There was no significant statistical difference between the two groups regarding major cardiac events during hospital stay (P value = 0.56). Regarding 6months follow up, there was no significant statistical difference between the two groups regarding CVS (P value = 0.17), but there was statistically significant difference regarding re-infarction, re-hospitalization and highly significant difference regarding HF (P:<0.001), in favor of group II characterized by high MPV. In our study, we observed a negative relation between admission MPV and subsequent EF. For this reason, in acute anterior STEMI patients, a high MPV may play an alerting role for possible LV dysfunction