In 963 patients, participating in a randomized study of low molecular weight heparin in unstable coronary artery disease and followed for 5 months, troponin T was determined. In the 766 patients with a pre-discharge exercise test both troponin T level and exercise test response were independent predictors of prognosis. Cardiac death or myocardial infarction occurred in 5, 9 and 13% of the patients with a maximal troponin T level of < 0.06 (n = 154), 0.06-0.2 (n = 175) and > or = 0.2 microgram.l-1 (n = 437), respectively. Based on exercise tolerance and occurrence of ST depression, patients with a low (n = 361), intermediate (n = 325) and high risk (n = 80) exercise test response were identified. In these, death or myocardial infarction occurred in 5, 13 and 29%, respectively. The combination of troponin T and the exercise test response allowed an even better categorization into low (n = 84), intermediate (n = 406) and high (n = 276) risk groups with 1, 7 and 20% death or myocardial infarction, respectively. Among those 197 patients unable to perform an exercise test the incidence was 3, 16 and 27% in patients with troponin T < 0.06, 0.06-0.2 and > or = 0.2 microgram.l-1, respectively. Thus, troponin T determinations and pre-discharge exercise tests alone and combined are valuable for risk assessment in unstable coronary artery disease.