A consecutive series of 184 patients with acute myocardial infarction (AMI) received thrombolytic therapy. The first 63 were treated in the catheterization laboratory with intracoronary streptokinase (IC-STK), and 44 (70%) had successful thrombolysis. One hundred twenty-one patients received intravenous (IV) STK immediately after diagnosis of AMI, and 99 (82%) were found to have an open infarct artery. Only 58% of patients (14 of 24) who required transfer from out-of-town hospitals for IC-STK treatment had successful thrombolysis; in contrast, IV-STK given in the local hospital resulted in an 85% (72 of 85) rate of thrombolysis (p = 0.005). IV-STK thus appears at least as effective as IC-STK for AMI and is more effective for patients treated in hospitals without catheterization facilities.