It has been widely reported that vitamin D deficiency is associated with Coronary heart disease (CHD), especially acute Myocardial infarction (MI). Many factors are responsible for reduced Left ventricular ejection fraction (LVEF) and acute Left ventricular fraction (LVF) after acute MI. This cross sectional descriptive type of study was conducted in the Cardiology department of Mymensingh Medical College Hospital from October 2017 to March 2019 to investigate the relationship of plasma vitamin D with LVEF in patients with first attack of acute MI. Total 185 patients of first attack of acute MI were included considering inclusion and exclusion criteria. Fasting blood samples were analyzed for plasma vitamin D level. Sample population were grouped at first into two, normal and low vitamin D level, taking 30ng/ml as cut-off value, low vitamin D level is further subdivided into insufficiency (21-29ng/ml), deficiency (10-20ng/ml) and severe deficiency (30ng/ml), 47.60±8.24% of patients having vitamin D insufficiency (21-29ng/ml), 44.38±8.12% of patients having vitamin D deficiency (10-20ng/ml) and 40.61±8.64% patients having severe vitamin D deficiency (<10ng/ml), which was statistically significant (p<0.05). So, low plasma vitamin D level is associated with reduced LVEF in patients hospitalized with first attack of acute MI.