Background: Serum soluble ST2 levels are elevated early after acute myocardial infarction (AMI) and are associated with lower pre-discharge left ventricular (LV) ejection fraction and adverse cardiovascular outcomes. Objectives: This study aimed to evaluate the efficacy of measuring serum soluble ST2 level in prediction of development of heart failure in patients with acute ST elevation myocardial infarction (STEMI) treated with primary percutaneous coronary intervention (PPCI). Methods and Results: This study included 24 STEMI patients, with their age ranged from 34 to 72 years with a mean age of 56.71±9.59 years. All of cases underwent successful PPCI. Serum soluble ST2 level was measured at index presentation and at follow up after 30 days, and assessed the cases clinically. Echocardiography are used for assessment of development of cardiac muscle dysfunction. Patients diagnosed as having HF had statistically significant higher levels of ST2 than other patients at 30 days follow up. A highly significant positive correlation was shown between ST2 level and LVMI. Serum soluble ST2 level revealed significant positive correlation with degree of diastolic dysfunction at time of presentation. Conclusions: Measurement of serum soluble ST2 level, after acute STEMI managed with primary PCI can help prediction of both early and delayed onset heart failure development.