Aims: To investigate the prognostic value of T-wave abnormalities in patients with non-ST-segment elevation acute coronary syndromes (NSTE-ACS), and whether such ECG changes may predict benefit from an early coronary angiography. Although ST-segment changes are considered the most important ECG feature in NSTE-ACS, T-wave abnormalities are the most common ECG finding. We hypothesize that a new quantitative approach to T-wave analysis could improve the prognostic value of this ECG abnormality. Methods and results: Quantitative T-wave analysis was performed on the admission ECG in 1609 patients with NSTE-ACS. Nine different categories of T-wave abnormality were analysed for their prognostic value concerning clinical outcome in patients not randomized to early coronary angiography. Also, the presence of one category (i.e. T-wave abnormality in >6 leads) was analysed for its predictive value concerning benefit from early coronary angiography. The combined study endpoint was death or myocardial infarction at 1 year follow-up. Patients with >6 leads with abnormal T-waves and concomitant ST-segment depression had a higher risk when not receiving early coronary angiography (24 vs. 12%, respectively; P = 0.003), but could be brought to the same level of risk as the remaining patients with this treatment. For non-invasively treated patients five different categories of T-wave abnormality were significantly associated with an adverse outcome. Conclusion: New quantitative T-wave analysis of the admission ECG gives additional predictive information concerning clinical outcome and identifies patients who benefit from early coronary angiography.