Background/aim: The aim of this study was to evaluate if the modified ACEF (age, creatinine, and ejection fraction) score is a predictor of major adverse cardiac and cerebrovascular events during 1 year of follow-up in patients with ST-segment elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI). Materials and methods: We retrospectively enrolled 1632 consecutive patients who were admitted to our emergency department diagnosed with STEMI within 12 h of chest pain and treated with primary PCI. The modified ACEF score, determined with a simplified scoring system, was calculated. The patients were grouped into tertiles according to this score (group I mACEF < 1.03, group II mACEF 1.03-1.37, group III > 1.37) . The clinical and angiographic data were compared among the tertiles. Results: In patients with the highest mACEF tertile, out-of-hospital cardiac arrest (1.3%, 1.8%, and 4.1% consecutively; P = 0.003), Killip class ≥ II (P < 0.001), and cardiogenic shock were more common and ejection fraction was lower (P < 0.001). Moreover, in the 1-year follow-up, there was a statistically significant difference between cardiac mortality, target vessel revascularization, stroke, reinfarction, and major adverse cardiac and cerebrovascular events of the groups, while the rates of stent thrombosis were similar. Conclusion: The modified ACEF score is a predictor of cardiac mortality and morbidity during 1-year follow-up.