Injury to the myocardial tissue due to ischemia and reperfusion occurs because of imbalance between the formation of oxidants and available antioxidants in the heart. Levels of vitamin C (ascorbic acid) and vitamin E (alpha--tocopherol) were evaluated in 52 patients of acute myocardial infarction (AMI) treated by streptokinase. They were further divided into reperfused group (39 patients) and non-reperfused group (13 patients). Twenty normal healthy subjects served as controls. Vitamin C and vitamin E were estimated in study group before and after thrombolytic therapy and in controls. Vitamin C levels were low in AMI cases as compared to controls (8.74 +/- 1.87 and 10.63 +/- 3.26 mg/L, respectively, P < 0.001). Trend of fall in vitamin C levels in the two study groups was not statistically significant. Vitamin E levels declined from 12.19 +/- 6.71 to 9.96 +/- 6.50 mg/L by 4 hours which was significant (P < 0.01) in the reperfused group, but the change in non-reperfused group (9.28 +/- 6.37 to 9.35 +/- 6.07 mg/dL by 4 hours) was non-significant. This is because of increased consumption of this antioxidant in suppressing the oxidative stress which occurs with reperfusion. Vitamin E can be proposed as a valid marker for reperfusion.