Patients who suffer acute myocardial infarction are heterogeneous and prognosis differs widely. High-risk patients are likely to derive the greatest benefit from treatment in an intensive care unit and from early thrombolytic therapy. A study was undertaken to determine those clinical parameters, available on admission to hospital, which would predict early death (within the first 30 days) and in this way to define high-risk patients. From July 1985 to December 1987, 233 patients admitted to J. G. Strijdom Hospital with acute myocardial infarction were prospectively evaluated. A total of 30 variables, including clinical, ECG and biochemical parameters, were recorded for each patient on admission. During the study period 36 patients (15.5%) died. The following variables were significantly associated with early mortality: age, Killip class, infarct location, height of ST-segment elevation and raised blood urea level. Using data readily available on admission to hospital, patients at highest risk of early death can be identified.