Background: Fibrinolytics are the commonest modality of treatment in ST elevation Mi in India. However there is paucity of data regarding successful ST resolution and diurnal its variation Material and Methods 150 cases of acute ST elevation MI were administered Thrombolytics(Streptokinase-104 and Tenecteplase-46) in a coronary care unit at a tertiary hospital in Delhi. ST resolution on ECG was assessed at 30,60,90,120 and 180 minutes post Infusion. Percentages of patients going ST resolution was compared by Kaplan Meir Survival plot. Complications and Adverse Effects of Thrombolytics was noted. Results Tenecteplase had a significantly faster rate of successful ST resolution than Streptokinase . Hazard ratio 1.7(95% C.I. 1.093-2.66, p=0.02). Diurnal variation was associated with ST resolution(r=-0.17,p<0.001) and onset of symptoms(r=-0.17,p=0.03) which was worse in mornings. Safety Profile of both drugs was similar. Conclusion: Our study shows that tenecteplase is associated with faster complete ST resolution. Streptokinase has a good safety profile but higher allergic reactions. There is a circadian variation in onset and severity of Myocardial infarction which is attenuated in Diabetic subgroup.