The objective of the present study is to find out whether the increased serum homocysteine level is associated with the increased serum troponin I as a surrogate marker of extent of myocardial injury in acute myocardial infarction patients. Elevated homocysteine levels are associated with increased thrombosis. In patients presenting with Acute Coronary Syndrome (ACS), it is not known whether this association is reflected in the degree of myocardial injury. This was a cross sectional study conducted among the patients with acute myocardial infarction in the Department of Cardiology, Dhaka Medical College Hospital during the period of October 2009 to September 2010 and which included 194 consecutive patients with acute myocardial infarction. The mean (+/- SD) serum homocysteine level was 20.2 +/- 14.3 micromol/L with range from 7.4 to 129.1 micromol/L. Mean serum troponin-I level was classified according to normal (<15 micromol/L) and high (> or = 15 micromol/L) levels of serum homocysteine values. The mean serum troponin-I level was 8.9 +/- 8.6 ng/ml in the patients having normal serum homocysteine level and 18.4 +/- 6.5 ng/ml in the patients having high serum homocysteine level. A significant positive correlation (r=0.273; p<0.001) was found between serum troponin-I level with homocysteine level. Patients with moderate hyperhomocysteinemia (> or = 15 micromol/L) was found to be 7.09 times more likely to have increased serum troponin-I (a surrogate marker of extent of myocardial injury). The main observation of the present study was that elevated serum homocysteine level has a positive correlation with serum cardiac troponin-I in patients with acute myocardial infarction. So serum homocysteine is associated with increased extent of myocardial injury as measured by serum cardiac troponin-I level, a surrogate marker in patients with acute myocardial infarction.