In 1985 an overview of clinical trials confirmed that patients treated within 6 h of the onset of symptoms of myocardial infarction benefited from thrombolytic therapy. Doubt remained about treatment later than this and this uncertainty prompted further randomised studies. The South American multicentre trial EMERAS is one of these. 4534 patients entering hospital up to 24 h after the onset of suspected acute myocardial infarction were randomised between intravenous streptokinase (SK) 1.5 MU and placebo, during the period January, 1988, to January, 1991. Once the results of ISIS-2 were known, only patients presenting more than 6 h after symptom onset were randomised. There was no significant difference in mortality during the hospital stay (269/2257 [11.9%] deaths among SK patients vs 282/2277 [12.4%] in controls). Among the 2080 patients presenting 7-12 h from symptom onset there was a non-significant trend towards fewer deaths with SK (11.7% SK vs 13.2% control; 14% [SD 12] reduction with 95% confidence interval [CI] of 33% reduction to 12% increase), whereas there was little difference among the 1791 patients presenting after 13-24 h (11.4% vs 10.7%; 8% [16] increase with a 95% CI of 20% reduction to 45% increase). These 95% CIs are wide and are consistent with the results of previous studies among patients presenting late after symptom onset. The EMERAS results, though not conclusive on their own, do contribute substantially to accumulating evidence on the question of whether fibrinolytic therapy really does produce any worthwhile improvement in survival among such patients.