The benefits and risks of acute reperfusion therapy (RT) in acute ischaemic stroke (AIS) remain uncertain in older patients, especially in nonagenarians. We aimed to assess the impact of RT in this population. Single-center retrospective cohort study comparing patients ≥ 90 years old admitted to a Stroke Unit (2008-2018) with AIS, submitted or not to RT [intravenous thrombolysis(IVT), mechanical thrombectomy(MT) or both]. Baseline characteristics, in-hospital complications and 3-month outcomes were compared. The primary outcome was 3-month “favorable outcome”, defined as modified Rankin Scale score 0-2 or equal to pre-stroke. Secondary outcomes were haemorrhagic transformation (HT) and 3 months mortality. We included 167 patients (median age 92 years, 66.5% females); 46.1% underwent RT (59 IVT, 11 MT, 7 both). RT group had higher admission National Institutes of Health Stroke Scale (NIHSS) (16 versus 9.5, p < 0.001). Favorable outcome occurred in only 22% of patients, with no differences between groups; its odds decreased with higher NIHSS scores (OR 0.80, 95%CI 0.73-0.87, p < 0.001) and with the development of in-hospital respiratory infection (OR 0.22, 95%CI 0.07-0.67, p = 0.007). HT occurred in 16.2% of patients, being more prevalent (26.0% versus 7.8%, p = 0.001), symptomatic (14.3% versus 3.3%, p = 0.011) and severe (PH1/2 15.6% versus 2.2%, p = 0.012) in the RT group, although it did not influence the primary outcome. Mortality was 32% at 3 months, with no difference between groups. Although patients submitted to RT had worse admission NIHSS and increased HT, they had similar functional outcome at 3 months. Stroke severity and in-hospital respiratory infections were the most important predictors of 3 months' functional outcome.