160 patients with first attack of acute myocardial infarction (AMI), admitted within 6 hours after onset of chest pain, were divided into two groups--80 receiving intravenous streptokinase (IVSK, Gr. I) an 80 being treated without IVSK (GR. II). They were studied for pre-discharge (12.5 +/- 2.5 days-post admission) echocardiographic LV function. Gr. I pts received 1.5 million units of IVSK within 6 hrs of onset of chest pain, alongwith beta-blockers, aspirin and heparin unless contraindicated. Gr. II received all these except IVSK alongwith conventional therapy. Highly significant (P < 0.001) improvement was noted in the end-diastolic volume (EDV), end-systolic volume (ESV), Ejection fraction (EF) and regional wall motion score (RWMS) in the anterior wall (AW) AMI group when treated early with IVSK. In the inferior wall (IW) AMI group significant decrease was observed in the EDV and ESV (P < 0.001) and RWMS (P < 0.05), but the difference was not statistically significant for EF. Early high-dose short term IVSK infusion is thus associated with highly significant improvement in LV functions--regional as well as global--especially in AW AMI; in IWAMI the improvement is less marked.