Objective: To analyze the cost-effectiveness of shorter delays to treatment and increased thrombolysis rate as shown in the PHANTOM-S (Prehospital Acute Neurological Treatment and Optimization of Medical Care in Stroke) Study. Methods: In addition to intermediate outcomes (time to thrombolysis) and treatment rates, we registered all resource consequences of the intervention. The analyzed treatment effects of the intervention were restricted to distribution of IV thrombolysis (IVT) administrations according to time intervals. Intermediate outcomes were extrapolated to final outcomes according to numbers needed to treat derived from pooled IVT trials and translated to gains in quality-adjusted life-years (QALYs). Results: The net annual cost of the Stroke Emergency Mobile (STEMO) prehospital stroke concept was 963,954. The higher frequency of IVT administrations per year (310 vs 225) and higher proportions of patients treated in the early time interval (within 90 minutes: 48.1% vs 37.4%; 91-180 minutes: 37.4% vs 50%; 181-270 minutes: 14.5% vs 12.8%) resulted in an annual expected health gain of avoidance of 18 cases of disability equaling 29.7 QALYs. This produced an incremental cost-effectiveness ratio of 32,456 per QALY. Conclusions: Depending on willingness-to-pay thresholds in societal perspectives, the STEMO prehospital stroke concept has the potential of providing a reasonable innovation even in health-economic dimensions.