Exercise testing early post AMI was evaluated as a predictor of reinfarction in patients treated with thrombolytics. AMI patients exercise-tested prior to discharge were included in the study (n = 178). The patients were followed for 2.9 +/- 0.9 years (mean +/- 1 SD) for the development of new cardiac events defined as cardiac death or reinfarction. Cox regression analysis of clinical and exercise test variables showed that there was significant predictive value of treating heart failure with drugs from two or more therapeutic groups (P < 0.001; hazard ratio 9.4 (3.1-28.2) (estimate and 95% confidence interval)), such as those with a previous history of myocardial infarction (P = 0.001; hazard ratio 4.0 (1.7-9.6)) and of significant ST depression (P = 0.029; hazard ratio 2.5 (1.1-5.7)). Significant ST depression could be substituted by the delta ST/delta HR index (P = 0.042; hazard ratio 2.8 (1.2-6.8)). The exercise test had independent but limited prognostic value in AMI patients treated with thrombolytics. The delta ST/delta HR index did not improve the predictive value of the exercise test.