High frequency low amplitude signals that prolong the terminal portion of the QRS complex in the electrocardiogram are termed late potentials (LPs). It has been established for quite some time that the presence of LPs after acute myocardial infarction (AMI) is associated with an increased risk of ventricular tachyarrythmias and sudden cardiac death (SCD), and vice versa. It is also known that thrombolytic therapy after AMI significantly decreased the incidence of ventricular tachyarrythmias and SCD. The object of this study was to find out whether thrombolysis in AMI decreased the incidence of LPs. Fifty two male patients of the age group 41-46 years with first anterior wall AMI were studied. Thirty of them presented within 6 hours of chest pain and were given intravenous streptokinase (IVSK) in addition to conventional therapy. The remaining 22 received conventional therapy but no thrombolysis. There was no significant difference in these two groups regarding age, CKMB, hypertension, diabetes, smoking, prior use of beta blockers, and ejection fraction. Eight out of the 30 patients receiving IVSK were positive for LPs as against 13 out of the 22 in the control group. This difference was statistically significant (p > 0.02 < 0.01). Thus thrombolysis in the early hours of anterior AMI diminishes the incidence of LPs.