This study aimed to explore the prognostic impact of cognitive impairment on the long-term risk of major adverse cardiovascular events (MACEs) in older patients with non-ST-elevation acute coronary syndrome (NSTEACS) undergoing invasive treatment.Patients aged ≥75 years with NSTEACS undergoing an invasive strategy were included in the multicentre prospective study (NCT01933581). Montreal Cognitive Assessment was used to evaluate cognitive status at baseline (scores ≥26 classified as normal, <26 as cognitive impairment). Long-term follow-up data were obtained from electronic patient care records. The primary endpoint was MACE as a composite of all-cause deaths, reinfarction, stroke/transient ischaemic attack, urgent revascularisation and significant bleeding.239 patients with baseline cognitive assessment completed long-term follow-up. Median age was 80.9 years (IQR 78.2-83.9 years) and 62.3% were male. On 5-year follow-up, there was no significant difference in the occurrence of MACE between the cognitively impaired group and the normal cognition group (p=0.155). Cognition status was not associated with MACE (HR 1.37 (95% CI 0.96 to 1.95); p=0.082). However, there was significantly more deaths (p=0.005) in those with cognitive impairment. Kaplan-Meier survival analysis (log-rank p=0.003) and Cox regression analysis (aHR 1.85 (95% CI 1.11 to 3.08); p=0.018) revealed increased risk of all-cause mortality, even after adjusting for frailty and GRACE (Global Registry of Acute Coronary Events) score.Cognitive impairment in older patients with NSTEACS undergoing an invasive strategy was associated with long-term all-cause mortality. Routine cognitive screening may aid risk stratification and further studies are needed to identify how this should influence management strategies and individual decision-making in this patient group.NCT01933581.