Rapid Response System (RRS) is a system to prevent the occurrence of sudden hospital emergencies and to prevent code blue. RRS is a screening system based on biometric data obtained from hospitalized patients, and medical information systems are expected to contribute to its operation and effectiveness. St. Marriannna University School of Medicine Hospital has been introducing RRS in 2010, presenting many clinical data and promoting the importance of RRS in Japan. The following medical institutions have implemented original and advanced systems to reduce the human burden and achieve high effectiveness, and we will present the details of the systems, the problems that led to their implementation, and their clinical effectiveness. Kyoto Prefectural University of Medicine has created a system to identify RRS subjects based on information from the hospital information system, and has already provided the system to more than a dozen hospitals. Tokyo Metropolitan Hiroo Hospital is testing a system that selects system activation targets from the hospital information system in the process of establishing the RRS, and then sends a bulletin to certified nurses via voice communication through a PHS line. The National Hospital Organization Osaka National Hospital has implemented a system that records the details of treatment of a patient with a sudden change in medical condition in real time at high speed and in detail in the electronic medical record, and automatically extracts treatment and prescriptions from the recorded contents and issues an order.