Fully computerized hospital information systems (HIS) are spreading in Japanese hospitals. Most HIS consist of server computers, terminals, a database, and a LAN. The introduction of HIS has enabled quick communication between doctors and staff and the immediate dissemination of patient information. Installation of a wireless data communication system compatible with a HIS has been reported to improve efficiency. However, also necessary is a voice communication system that can transmit instructions quickly in emergencies, such as a sudden change in the health status of an inpatient. In the Japanese medical community, "An environment in which access and the sharing of information are possible anywhere and at all times" is called a "ubiquitous environment." In order to attain such an environment, a telecom infrastructure with a mobile communications network is very important to voice and data communication. Here, we show the "ubiquitous environment" realized in Shimane University Hospital and how it has improved efficiency.