Abstract Aims The role of coronary calcification on clinical outcomes among different revascularization strategies in patients presenting with acute coronary syndromes (ACSs) has been rarely investigated. The aim of this investigation is to evaluate the role of coronary calcification, detected by coronary angiography, in the whole spectrum of patients presenting with acute ACS. Methods and results The present study was a post hoc analysis of the MATRIX programme. The primary endpoint was major adverse cardiovascular events (MACE), defined as the composite of all-cause mortality, myocardial infarction (MI), or stroke up to 365 days. Among the 8404 patients randomized in the MATRIX trial, data about coronary calcification were available in 7446 (88.6%) and therefore were included in this post hoc analysis. Overall, 875 patients (11.7%) presented with severe coronary calcification, while 6571 patients (88.3%) did not present severe coronary calcification on coronary angiography. Fewer patients with severe coronary calcification underwent percutaneous coronary intervention whereas coronary artery bypass grafting or medical therapy-only was more frequent compared with patients without severe calcification. At 1-year follow-up, MACE occurred in 237 (27.1%) patients with severe calcified coronary lesions and 985 (15%) patients without severe coronary calcified lesions [hazard ratio (HR) 1.91; 95% confidence interval (CI) 1.66–2.20, P < 0.001]. All-cause mortality was 8.6% in patients presenting with and 3.7% in those without severe coronary calcification (HR 2.38, 1.84–3.09, P < 0.001). Patients with severe coronary calcification incurred higher rate of MI (20.1% vs. 11.5%, HR 1.81; 95% CI 1.53–2.1, P < 0.001) and similar rate of stroke (0.8% vs. 0.6%, HR 1.35; 95% CI 0.61–3.02, P = 0.46). Conclusion Patients with ACS and severe coronary calcification, as compared to those without, are associated with worse clinical outcomes irrespective of the management strategy.