Introduction: Elevated plasma concentrations of lipoprotein {Lp(a)} have been consistently shown to be a risk factor for the development of a spectrum of thrombotic and atherosclerotic disorders including Coronary Artery Disease (CAD). Aim: To assess relationship of Lp(a) with severity of CAD in patients of Acute Myocardial Infarction (AMI). Materials and Methods: A hospital based, cross-sectional study was conducted at Topiwala National Medical College and B.Y.L. Nair Charitable Hospital, Mumbai, Maharashtra, India, between November 2016 to April 2018 (18 months). A total of 200 diagnosed cases of AMI who were willing to undergo coronary angiography were enrolled for this study. Prior to coronary angiography, a fasting blood sample was assessed for lipids and Lp(a) levels. The Synergy between Percutaneous Coronary Intervention with TAXUS and Cardiac Surgery (SYNTAX) score was calculated according to the coronary angiography results. Patients were divided into two groups based on Lp(a) levels: <25 mg/dL and >25 mg/dL and categorised based on CAD severity and SYNTAX scores as low (<22), intermediate (23-32) and high (>32). Lp(a) levels were categorised as low (<25 mg/dL) and high (>25 mg/dL). A p-value of <0.05 was considered as statistically significant. The statistical evaluation of data was done using the Statistical Package for Social Sciences (SPSS; Chicago, IL, USA) program, version 20.0. Results: Majority of the patients belonged to the age group 41- 60 years. Males comprised 161 (80.5%) patients of the study population. Hypertension was the most prevalent risk factor, observed in 101 (50.5%) patients. Left ventricular ejection fraction <40% was observed in 85 (42.5%) patients. Majority had low SYNTAX score {92 (46%)}. There was a significant difference in patients with Lp(a) <25 mg/dL compared to patients with Lp(a) >25 mg/dL with low (45.7% vs. 54.3%, p-value=0.0001), intermediate (9.9% vs. 90.1%, p-value=0.0001) and high SYNTAX scores (10.8% vs. 89.2%, p-value=0.0001), respectively. Conclusion: The Lp(a) was significantly associated with severity of CAD and it also displays prognostic significance.