A retrospective casenote audit of the use of thrombolysis in 212 of 335 patients with acute myocardial infarction (63%) was carried out on the coronary care unit of a Sheffield teaching hospital. The overall inpatient mortality was 17%, 12% in the thrombolysis group and 26% in the remainder (p < 0.005). Patients aged 75 years or older were less likely to die if they received thrombolytics (p < 0.05) despite an excess of anterior myocardial infarctions in the thrombolysis group (p < 0.01). The infusion of streptokinase had to be stopped in rive patients (4%) because of allergy or arrhythmias. Thrombolytic therapy was considered in all patients with acute myocardial infarction; it was withheld inappropriately in eight cases and given inappropriately in two. Thrombolysis produced clear benefits in mortality for all patients, including those over 75 years old. There was a high rate of use of thrombolysis which was generally safe and appropriate, although adjustments to the guidelines may allow even more patients to receive this therapy.