Necessity of establishing a national information network in medicine is beginning to be recognized in Japan.The trend has been more prominent in the United States where the National Library of Medicine's MEDLARS is actually being operated with its satelite centers located in not only various parts of the country but also in England, in Sweden and now in Australia. Herner's design for a medical library and information system, recommended to the Department of Health, Education and Welfare in 1966, was a plan of very large scale but it had many subsystems already in existence to build up the main scheme on them. The basic idea of this plan might be adaptable in planning our national information system but changes will be necessary to make it fit to our situation.In Japan, medical libraries are fairly active in literature providing services but not so in information services. For instance, out of 51 member libraries of the Japan Medical Library Association, only few of them are doing literature search as their regular service. But on the other hand, these 51 member libraries which include all of 46 medical school libraries, with the total of 3,754,808 bound periodical volumes and books, and subscription of 51,453 periodical (5,036 different titles), lent out 626,612 volumes to their areas, and sent to other member libraries 42,831 of their library materials and their photo copies as interlibrary loan in one year from April 1966 to March 1967. The association divides Japan into 9 districts to serve but the members are not divided evenly. In the case of Kanto district, there are 18 member libraries out of all 51 and they have 1,228,331 volumes, or 32.7% of all 3,754,808 volumes.The units which are to be included in the proposed information network in Japan are these, such as, a national center, district centers, specialized centers, data ceters, interlibrary centers, and the units with clearing house function.The national center will have a wholesale dealer's function in handling literature and switching information. District centers are depending on the national center for the supply of literature and processed information, but they are also the central unit in their own districts. Specialized centers collect all the materials in a certain special subject field, analyse their contents and provides an answer to the requested question in the field. Data center will do similar function but they will handle data and not information. For interlibrary centers which we don't have anything of the sort at the moment, will be set up after the model of the New York Medical Library Center.To carry out this plan, establishment of the national center will be the first and the largest problem of all. The Japan Information Center of Science and Technology (JICST) will be the only possible candidate for this though it is a new comer in medical field and it does not have a large enough medical collection nor experience of handling medical information.But the JICST decided to extend there serving fields to include biomedicine and agriculture. The JICST also is negotiating with the National Library of Medicine in Bethesda on setting up a MEDLARS' searching center in it. Therefore, with close cooperation from the Japan Medical Library Association and its member libraries, it can grow into a satisfactory national center. As for the district centers, 10 or 12 of the largest and most active medical school libraries should be selected and strengthened to make them possible to do their role. Specialized centers, data centers and inter library centers are the ones which should be built up from nothing. An inter library center will be necessary in each of the east and west Japan areas. The national referral center and an information center on “who's doing what research in medicine” should be established in the national center but with help in gathering the needed information for the service from the member libraries of the Japan Medical Library Association. The weak points of the plan are:The necessity of organizing a national network of medical information handling is not fully recognized by researchers, clinicians, and faculty members of the medical schools.There is no medical information system of any size which can be a core or a subsystem of the network, except the Japan Medical Library Association's interlibrary loan system.