This research aims to provide the protocol to achieve efficient information exchange by electric means between the health-checkup (HCs) facilities. Joint Working Group of JMHTS (Japan Society of Multiphasic Health Testing and Service) and JAHIS (Japanese Association of Healthcare Information Systems Industry vender) developed a health/medical data interchange model that is based on the markup information structure. Our data encoding language, HDML (Health-checkups Data Markup Language), was based on SGML, which has context free grammar. HDML had the standard DTD which defined anamnesis, physical examination, laboratory examination, summary findings, and judgment of total health status, etc. The laboratory examination contains the following items: item’s name, method, unit, device, company name, product name, principle, and standard reference value. (Fig.1) We take into account the interchangeability of data with HL7 and other international standard protocols. As a preliminary study, we carried out an experimental trial in October 1999, which transferred laboratory data by translating into HDML, from 2 HCs facilities to other 2 HCs facilities. We have succeeded in transferring almost all laboratory data appropriately by using the HDML protocol software between the HCs facilities. Moreover, we could convert and standardize the laboratory data properly from the attribute information written in the DTD.(Fig.2) We propose the HDML protocol to standardize health/medical data that will make available for multi-health facilities on the basis of the standardization of data exchange regarding HCs. We found this HDML protocol worked effectively in using the actual health/medical data.