OBJECTIVE To evaluate the experience with i.v. streptokinase (SK) in the treatment of acute myocardial infarction (AMI) in two cardiac care units. Conception: Retrospective analysis of patients (pts) admitted either to UCIM or UTIC-AC with the diagnosis of AMI receiving SK. METHODS 77 pts were treated, although one of them was later proved to be a false positive diagnosis of AMI. Of the other 76, there were 63 men and 13 women with age 55 +/- 12 (mean age +/- SD) years (limits of 20 and 82 years). AMIs were anterior in 42% of the pts, inferior in 51%, anterior and inferior in 4% and non Q wave in 1%; Killip classes (cl) were: cl I in 64%, cl II in 26%, cl III in 5% an cl IV in 5%. The time interval from the beginning of acute symptoms to the arrival at the hospital was 2.8 +/- 1.2 hours (1 to 15) and from that moment to administration of SK was 1.6 +/- 1.4 h. The whole interval to the administration of SK was 4.4 +/- 2.5 h. RESULTS The 3 criteria of reperfusion (pain relief, ST changes resolution and less than 18 h maximum CK rise) were present in 36% of the pts, 2 of the criteria in 21%, and 41% of the pts had only one or no criteria. The time interval to the administration of SK in these 3 groups was 3.3 +/- 1.3 h, 4.8 +/- 3.1 h and 5.0 +/- 2.5 h respectively. Non fatal complications occurred in 16% of the pts (major bleeding in 2.6%, minor bleeding in 99% and minor anafilaxy in 4%. Mortality was 11.8% (9 pts). Two thirds of the deaths were due to cardiac rupture. In hospital residual ischemia was present in 9% (7 pts). CONCLUSIONS Treatment of AMI with i.v. SK proved to be a safe and easy to apply therapeutic option, carrying a low morbidity and mortality, lower than that normally observed in our hospital with the conventional approach of AMI before the era of thrombolysis.