To reduce prehospital delays in patients with cerebrovascular events, we performed a population-based, cluster-randomized trial. Cluster units were 48 zip code areas in the catchment area of 3 inner-city hospitals in Berlin, Germany. The intervention consisted of information material and reminders focusing on the importance of calling the emergency medical services in case of an acute event. A total of 741 patients were admitted from the control areas and 647 from the intervention areas. The intervention significantly reduced time to hospital by 27% in women, whereas no effect was found in men. Future research needs to focus on transferability, sustainability, and sex-specific aspects of the intervention.