Thrombolytic therapy has been shown to preserve left ventricular function and reduce mortality in the acute phase of myocardial infarction. When the usual inclusion criteria are respected, only about 30% of patients can benefit from this form of treatment. The "excluded" cases are more numerous and have a worse prognosis. This has led to a review or the indications, especially with respect to age and the maximum time delay before instituting treatment. The data currently available comes mainly from large from retrospective analyses of subgroups taken from large scale thrombolytic trials, and must be confirmed by randomized studies specifically designed to analyse these problems. In elderly patients, the benefits in terms of mortality are important but the haemorrhagic risk is also greater and has to be accurately evaluated. Age by itself should not be considered to be an absolute contraindication to thrombolytic therapy which may be undertaken in elderly patients with large infarcts after having carefully excluded the other contraindications frequently observed in this age group. Late thrombolysis probably acts by mechanisms other than limitation of infarct size. The results are less impressive than when thrombolysis is instituted early require confirmation by the randomised studies currently under way. However, at present, is seems justified to prescribe thrombolytic therapy after the 6th hour in patients with large infarcts who continue to have chest pain. The limitations of thrombolytic therapy with regards to age and delay of administration should, therefore, be reconsidered taking into account the individual risk benefit ratio.