The aim of our study was to redesign and evaluate the Computerized Prescribing System (PRS) to reduce physicians' workload and improve patient safety. The study was conducted in 2 prefectures in Japan. 186 physicians were surveyed with regard to prescription by physicians and medical office assistants. As a result, it was found that physicians demanded support from medical office assistants with regard to entry of prescription orders but for limited types of medicines. Based on our findings, we developed recommendations for a redesigned outline for PRS for the following 4 scenarios: (1) Continue prescription; (2) narcotic medicines; (3) chemotherapeutic medicines; and (4) medicines used in medical procedures. The outline was evaluated for effectiveness and safety and was confirmed to be a useful future prescription system.