There is a lack of knowledge on the interaction between age and left main coronary artery revascularization. The aim of this study was to investigate the comparative effectiveness of percutaneous coronary intervention (PCI) with drug-eluting stents and coronary artery bypass grafting (CABG) in patients with left main coronary artery disease aged <75 versus ≥75 years. Of a total of 894 patients included, 692 (77.4%) were aged <75 years and 202 (23.6%) ≥75 years. PCI was found to be significantly different from CABG with respect to the composite of major adverse cardiac events at 1-year follow-up in patients aged <75 years (15.5% vs 8.5%, p = 0.01) but not in those aged ≥75 years (16.4% vs 13.9%, p = 0.65). This finding was consistent after statistical adjustment for baseline confounders in the 2 groups (adjusted hazard ratio [AHR] 2.2, 95% confidence interval 1.2 to 4.1, p = 0.016 in younger patients; AHR 0.9, 95% confidence interval 0.3 to 3.0, p = 0.88 in older patients). In the 2 groups, PCI and CABG showed similar adjusted risks for all-cause death, cardiac death, and myocardial infarction. Target lesion revascularization occurred more frequently in patients aged <75 years treated with PCI compared to CABG (AHR 5.1, 95% confidence interval 1.9 to 13.6, p = 0.001) but not in those aged ≥75 years. A significant interaction between age and treatment with regard to major adverse cardiac events was identified (adjusted p for interaction = 0.034). In conclusion, compared to younger patients, elderly patients with left main disease are likely to derive the maximal gain from a less invasive procedure such as PCI.