ABSTRACT Acute myocardial infarction (AMI) is still a progressive disorder characterized by high morbidity and mortality. The circulating level of galectin-3 has emerged as a novel informative biomarker on the prediction of fibrosis, cardiac dysfunction, cardiac remodeling and the development and progression of heart failure. Objective: The aim of this study was to verify if serum galectin-3 level on hospital admission can predict myocardial remodeling in patients with STEMI undergoing primary PCI or not. Subjects and methods: We enrolled one hundred patients admitted to Zagazig university hospital, Egypt who underwent primary PCI for acute STEMI from April 2020 to June 2020 to study the predictive value of Galectin-3 on LV remodeling after AMI. Estimation of serum Galectin-3 at admission day and after 3 months of PPCI, along with echocardiographic indices of myocardial remodeling was done at admission day and after 3 months of PPCI. We retrogradely divided the patients into two groups in a case-control fashion according to occurrence of remodeling which was defined as dilatation of LV, decreased ejection fraction (EF) less than 50%, thinning of infarcted area and compensatory thickening of healthy area. So, the groups can be as follows: group I: Non-remodelers (n=44) and group II: Remodelers (n=56). Results: Regarding demographic data and clinical characteristics, there was no statistically significant difference between both groups. There was no statistically significant difference between both groups regarding MI territory (thus both groups were well-matched). There was statistically non-significant difference between both groups regarding baseline TIMI flow (p: 0.9), but post primary PCI, the remodelers group had significantly worse TIMI flow (p: 0.04). Both baseline and 3month serum Galectin level had statistically significant negative correlation with EF (P<0.001) and positive correlation with both LVESV, LVEDV (P<0.001). Relying on receiver operating characteristics (ROC) curve, we concluded that serum Galectin- 3 level at baseline is an independent predictor of remodeling occurrence (P<0.0001) with an area under the curve = 0.673 and cutoff value >15.8 ng/ml. Patients with LV systolic dysfunction after 3 months had higher baseline galectin-3 when compared to patients with preserved ejection fraction. Conclusion: Galectin-3 has been associated with fibrosis development and cardiac remodeling hallmarks of HF. We observed that baseline galectin-3 was independently associated with the development of LV dysfunction. We concluded that baseline galectin-3 has strong association with progressive cardiac remodeling after MI.