Purpose: Elderly patients, especially octogenarians, are underrepresented in recently published studies, that showed a benefit of endovascular stroke treatment (EST) for patients with acute basilar artery occlusion (BAO). We aimed to compare the clinical outcome of octogenarians with BAO and EST compared to younger patients and to identify independent outcome predictors. Methods: This is a retrospective, single-center analysis of patients treated for BAO with EST from 01/2013 until 06/2021 in a tertiary stroke center. Octogenarians were compared to younger patients. Study endpoint was the clinical outcome as per mRS 90 days after stroke onset. The study groups were compared in univariate analysis and a multivariate logistic regression analysis was performed to define independent predictors for clinical outcome. Results: In this study, 74/191 (38.7%) octogenarians had a higher pre-stroke mRS (median, IQR 2, 1 - 3 vs. 0, 0 - 1 in younger patients, p < 0.001) and a comparable NIHSS before EST (median, IQR 21, 8 - 34 vs. 22, 10 - 38 in younger, p = 0.712). They showed a comparable mRS 90d after stroke onset (median, IQR 5, 3-6 vs. 5, 2-6 in younger), p = 0.194), but less often a good clinical outcome (mRS 0-2: n = 27, 23% younger vs. n = 9, 11.7% octogenarians, p = 0.004). The rate of bad clinical outcome was comparable (mRS 5-6, n = 63, 46.7% younger vs. 39, 50.6% octogenarians, p = 0.194). Baseline NIHSS was a stable independent predictor for clinical outcome in both study groups (e.g. for bad clinical outcome: in octogenarians OR 1.04 CI 100 - 10.85, p = 0.0019, in younger OR 1.061, CI 1.027 - 1.098, p = 0.005) Conclusion: Octogenarians with acute BAO eligible for EST are less likely to be functionally independent at 90 days after stroke onset, but the rate of death or severe handicap is comparable to younger patients. The admission NIHSS predicts clinical outcome in both age groups.