INTRODUCTION: We have demonstrated in a multicenter cohort that the COVID-19 pandemic has led to a delay in intravenous thrombolysis (IVT) among stroke patients. Whether this delay contributes to meaningful short-term outcome differences in these patients warranted further exploration. METHODS: We conducted a nested observational cohort study of adult acute ischemic stroke patients receiving IVT from 9 comprehensive stroke centers across 7 U.S states. Patients admitted prior to the COVID-19 pandemic (1/1/2019-02/29/2020) were compared to patients admitted during the early pandemic (3/1/2020-7/31/2020). Multivariable logistic regression was used to estimate the effect of IVT delay on discharge to hospice or death, with treatment delay on admission during COVID-19 included as an interaction term. RESULTS: Of the 676 thrombolysed patients, the median age was 70 (IQR 58-81) years, 313 were female (46.3%), and the median NIHSS was 8 (IQR 4-16). Longer treatment delays were observed during COVID-19 (median 46 vs 38 min, p = 0.01) and were associated with higher in-hospital death/hospice discharge irrespective of admission period (OR per hour 1.08, 95% CI 1.01-1.17, p = 0.03). This effect was strengthened after multivariable adjustment (aOR 1.15, 95% CI 1.07-1.24, p < 0.001). There was no interaction of treatment delay on admission during COVID-19 (pinteraction = 0.65). Every one-hour delay in IVT was also associated with 7% lower odds of being discharged to home or acute inpatient rehabilitation facility (aOR 0.93, 95% CI 0.89-0.97, p < 0.001). CONCLUSION: Treatment delays observed during the COVID-19 pandemic led to greater early mortality and hospice care, with a lower probability of discharge to home/rehabilitation facility. There was no effect modification of treatment delay on admission during the pandemic, indicating that treatment delay at any time contributes similarly to these short-term outcomes.