Thrombolysis is a new treatment for myocardial infarct patients, 162 such patients were studied: 62 received thrombolytic treatment and 100 a classical therapy. For cost-benefit analysis, all patients were followed for at least 1 year and received an identical questionnaire to assess the costs induced by this disease. At 1 year, 10% had died in the two groups. Patients who received thrombolytic treatment had a hospital stay 2 days longer, on average, but were readmitted for shorter periods (10.3 days less). Thrombolysis was more expensive (10,550 pounds vs 8998 pounds). Therefore, it is necessary to invest 150 pounds to reduce rehospitalization time by 1 day. Benefits were almost 31% greater for thrombolysis patients and the cost-benefit ratio was about 0.7. Thus the monetary benefits, initially rather negative, became positive at the end of the first year.