We evaluated the prognosis for 419 patients admitted to hospital due to suspected acute myocardial infarction (AMI) who developed ST-T changes, but no rise in serum enzyme activity, and compared it to that of 508 patients developing non-Q-wave AMIs. We conclude that these patients have a high 1-year mortality (13%), although significantly lower than in patients with non-Q-wave AMIs (31%). The mortality is higher in patients with only ST depression (n = 86; 22%) than in patients with only T-wave inversion (n = 264; 8%).