Abstract Background Acute coronary syndromes (ACS) are more challenging in elderly patients, particularly when related to multivessel disease (MVD). Concerns about outcomes, and the lack of evidence, lead to more conservative treatment. While benefits of complete revascularization are well established among the youngest, doubts persist in older patients. Despite FIRE trial having showed superiority of complete revascularization with coronary physiology, in older patients with ACS and MVD, more evidence is needed. Methods Multicenter retrospective cohort of 629 patients, older than 75 years, with ACS and MVD, was divided into complete or culprit-only revascularization groups. In-hospital outcome of death and major adverse cardiovascular events (MACE) and follow-up outcome of death and cardiovascular hospital admission were assessed. Results From the 629 patients, 383 (61%) were submitted to PCI, of which 66% (n=254) were submitted to culprit-only revascularization and 34% (n=129) to complete revascularization. Culprit-only group's mean age was 83±5 years and median age in complete revascularization group was 81 (IQ 78-84) years. There was similar number of female patients in both groups (42% and 37%, p=0,26), and the culprit only group was significantly older (p=0,006). There were more ST-segment elevation myocardial infarctions in culprit- only group (p<0,001). Regarding diabetes, previous ACS, Killip classification, heart failure, stroke, peripheral artery disease, and chronic kidney disease, there were no statistically significant differences between groups (p>0,05). Complete revascularization was associated with lower in-hospital events, with 36% against 48% in culprit-only (p=0,025 OR 0,62 [0,4-0,9]), mainly due to lower in-hospital deaths, with 3% against 13% (p<0,01 OR 0,3 [0,15-0,67]) but also due to lower in-hospital MACE with 29% against 27% (p=0,02 OR 0,6 [0,4-0,9]). The mean follow-up was 13±7 months, during which, in complete revascularization group, there was non-statistically significant decrease of deaths, with 13% against 15% (p=0,4), hospital readmissions, with 21,8%, in comparison with 24,9% (p=0,2), and composite outcome, with 35% and 40% (p=0,16) of composite events in the culprit-only group There was a non-statistically significant decrease of the mean for survival time for culprit only group which was 10±8 months comparing with complete group of 13±8 months (p=0,16). Conclusion In older patients with ACS and MVD the ideal strategy is yet to be determined. Still complete revascularization strategy showed a statistically significant decrease of in-hospital death and MACE, and non-statistically significant decrease in follow-up mortality and readmissions. This study suggests, like FIRE trial, that when clinically and anatomically feasible, it seems legit to attempt complete revascularization in elderly patients with ACS and MVD.