Vitamin B12 is a red colored, heat stable, water-soluble vitamin also called as Cobalamin or extrinsic factor of Castle. It contains only a single cobalt atom which is 4.35% by weight. It is absorbed in our body in ileum in presence of two factors intrinsic factor of Castle and cobalophilin. To find out the levels of homocysteine, vitamin B12 and folate in serum samples of patients of myocardial infarction and healthy control. To find association between hyperhomocysteinemia and Myocardial infarction. This study was carried out in our tertiary care hospital for a period of 2 months from 16 June 2022 to 14 August 2022. Study included 97 diagnosed cases with Myocardial Infarction (coronary artery disease). The diagnosis of Myocardial Infarction was made by Electrocardiograph (ECG) and serum levels of troponin I and Creatinine kinase-MB(CK-MB). The blood sampleswere taken from patients for conducting the study before angiography or before starting thrombolytics. Most of the cases taken up for project belonged to agegroup between 40-70 yrs, with maximum of 81 yrs and minimum age being 32yrs. We also took samples of 50 random normal age matched control who were healthy people from the society. Most of them were from age group between 40- 60 yrs. The serum was separated and analysed for vitamin B12 and folic acid levels using competitive binding receptor assay and competitive binding immuneenzymatic assay respectively. Plasma was analysed for total homocysteine usinga chemiluminescent micro particle immunoassay on auto analysers in biochemistry section of the central laboratory. In this study a negative correlationcould be established between hyperhomocysteinemia and vitamin B12 deficiency and positive correlation was seen in between patients with hyperhomocysteinemiaand myocardial infarction.