Background and Purpose—Prehospital redirection of stroke patients to a regional center is used as a strategy to maximize the provision of intravenous thrombolysis. We developed a model to quantify the benefit of redirection away from local services that were already providing thrombolysis. Methods—A microsimulation using hospital and ambulance data from consecutive emergency admissions to 10 local acute stroke units estimated the effect of redirection to 2 regional neuroscience centers. Modeled outcomes reflected additional journey time and accuracy of stroke identification in the prehospital phase, and the relative efficiency of patient selection and door-needle time for each local site compared with the nearest regional neuroscience center. Results—Thrombolysis was received by 223/1884 emergency admissions. Based on observed site performance, 68 additional patients would have been treated after theoretical redirection of 1269 true positive cases and 363 stroke mimics to the neuroscience center. Over 5 years redirection of this cohort generated 12.6 quality-adjusted life years at a marginal cost of £6730 ($10 320, €8347). The average additional cost of a quality-adjusted life year gain was £534 ($819, €673). Conclusions—Under these specific circumstances, redirection would have improved outcomes from thrombolysis at little additional cost.