Multivessel coronary disease is frequent in older patients who underwent coronary angiography for acute coronary syndrome. Whether a complete revascularization or a culprit-only approach is preferable in these patients is still debated. We included consecutive patients aged ≥85 years, presenting with acute coronary syndrome and showing multivessel coronary disease at coronary angiography. Patients were grouped according to complete (residual SYNTAX score [RSS] 0 to 8) or incomplete (RSS >8) revascularization. Primary end point was the rate of major adverse cardiovascular events (MACEs, the composite of cardiovascular death, re-myocardial infarction [re-MI], clinically driven percutaneous coronary intervention, and rehospitalization because of cardiac disease) at 2 years follow-up. A total of 166 patients met the criteria for enrollment; 108 patients had a final RSS 0 to 8 (complete revascularization) and 58 patients had a final RSS >8 (incomplete revascularization). The rate of MACE was reduced in patients who underwent complete revascularization (35.2% vs 51.7%, p = 0.039, adjusted hazard ratio 0.60, 95% confidence interval 0.37 to 0.98, p = 0.04), a difference mainly driven by a reduction in re-MI (8.3% vs 19.0%, p = 0.045), clinically driven percutaneous coronary intervention (2.8% vs 19.0%, p <0.001), and rehospitalization for cardiac disease (9.3% vs 24.1%, p = 0.009). Other independent predictors of MACE were active malignancy, previous MI, left ventricle ejection fraction <35% (increasing risk of events), and radial access (reducing risk of events). In conclusion, in patients aged ≥85 years, a complete revascularization is associated with a better prognosis, especially in terms of nonfatal events.