The University Medical Information Network (UMIN), established in 1989, is a network service organization for national university hospitals in Japan. It has provided various medical information services to medical professionals, including database, electronic mail, and news services. Although its initial network was constructed as a closed network using N1 protocol, it now adopts TCP/IP protocol and is open to other medical professionals via the Internet. The next UMIN network system is planned to be constructed as a secure virtual closed network on the Internet, using cipher technology, and to provide secure information services to national university hospitals via the closed network, and to other medical professional via the Internet. User friendly interface and flexible system development were made possible by adopting TCP/IP, and the number of users dramatically increased accordingly. However, the database, software design, and human organizations developed in the N1 era have now proven to be of great value, and contribute to todayís flourishing state of the UMIN.