To evaluate the diagnostic value of Copeptin as a novel biomarker in early diagnosis of Acute Myocardial Infarction. 56 patients with acute Myocardial Infarction (STEMI) and 25 healthy controls who were admitted to the Cardiology and Clinical Pathology Departments, national heart institute (NHI) from October 2015 to April 2016. The kit used a double-antibody sandwich enzyme-linked immune-sorbent assay (ELISA) to assay the level of Human Copeptin in samples. As regard copeptin, the median range of copeptin level was 242.5pg/ml in patient group and 75pg/ml in control group. The comparative study between the two groups shows a significant difference (p < 0.05) Conclusion: Copeptin is a reliable diagnostic tool in patients with AMI (STEMI) with sensitivity 85.7%, specificity 86.7%, PPV 96% and NPV 61.9%.