Patients with an acute basilar artery occlusion (BAO) have a high risk of long-lasting disability and death. Only limited data are available on functional outcome in elderly patients with BAO. Using data from the Basilar Artery International Cooperation Study, we aimed to determine outcomes in patients ≥75 years. Primary outcome measure was poor functional outcome (modified Rankin scale score 4-6). Secondary outcomes were death, insufficient vessel recanalization (defined as thrombolysis in myocardial infarction score 0-1) and symptomatic intracranial hemorrhage (SICH). Patients were divided into four age-groups, based on quartiles: 18-54, 55-64, 65-74, and ≥75 years. Outcomes were compared between patients ≥75 years and patients aged 18-54 years. Risk ratios with corresponding 95 % confidence intervals (CI) were calculated and Poisson regression analyses were performed to calculate adjusted risk ratios (aRR). We included 619 patients [18-54 years n = 153 (25 %), 55-64 years n = 133 (21 %), 65-74 years n = 171 (28 %), and ≥75 years n = 162 (26 %)]. Compared with patients aged 18-54 years, patients ≥75 years were at increased risk of poor functional outcome [aRR 1.33 (1.14-1.55)] and death [aRR 2.47 (1.75-3.51)]. Nevertheless, 35/162 (22 %, 95 % CI 15-28 %) of patients ≥75 years had good functional outcome. No significant differences between age groups were observed for recanalization rate and incidence of SICH. Although patients ≥75 years with BAO have an increased risk of poor outcome compared with younger patients, a substantial group of patients ≥75 years survives with a good functional outcome.