Aims: The prognostic significance of cardiac magnetic resonance (CMR)-derived infarct characteristics has been demonstrated in ST-elevation myocardial infarction (STEMI) cohorts but is undefined in non-ST-elevation myocardial infarction (NSTEMI) patients. We aimed to investigate determinants and the long-term prognostic impact of CMR imaging-derived infarct characteristics in patients with NSTEMI. Methods and results: Infarct size (IS), myocardial salvage index (MSI), and microvascular obstruction were assessed using CMR imaging in 284 NSTEMI patients undergoing percutaneous coronary intervention (PCI) in three centres. CMR imaging was performed 3 [interquartile range (IQR) 2-4] days after admission. The primary clinical endpoint was defined as major adverse cardiac events during median follow-up of 4.4 (IQR 3.6-4.9) years. Median IS was 7.2% (IQR 2.2-13.7) of left ventricular (LV) myocardial mass (%LV) and MSI was 65.7 (IQR 39.3-84.9). Age (P ≤ 0.003), heart rate (P ≤ 0.02), the number of diseased coronary arteries (P ≤ 0.01), and Thrombolysis In Myocardial Infarction (TIMI) flow grade before PCI (P < 0.001) were independent predictors of IS and MSI. The primary endpoint occurred in 64 (22.5%) patients. CMR-derived infarct characteristics had no additional prognostic value beyond LV ejection fraction in multivariable analysis. Conclusion: In this prospective, multicentre NSTEMI cohort reperfused by PCI, age, heart rate, the number of diseased coronary arteries, and TIMI flow grade before PCI were independent predictors of IS and MSI assessed by CMR. However, in contrast to STEMI patients there was no additional long-term prognostic value of CMR-derived infarct characteristics over and above LV ejection fraction. Clinicaltrials.gov: NCT03516578.