POSCO Health Care Center has collected health and environmental data using computerized system since 1987. One of the important roles of Industrial Health Care Center is to provide a comprehensive occupational health care, including therapeutic medical care, periodic medical examination and industrial hygiene control for the prevention of work-related illness. To strengthen the functions of an occupational health surveillance system since May, 1992, and it is scheduled to be completed by March, 1994. The modified POSCO Computerized Occupational Health Surveillance System (PCOHESS) contains three major area: health care, environmental monitoring, and personal information. The linkage among three area, lacking in the previous system, was emphasized in PCOHESS. The area of health care assists the management of preplacement examination data as well as the diseased and disabled data, and it will facilitate the preplacement for new employees and will enable an efficient care for the diseased and disabled. Environmental and personal sampling data, and personal information data, such as age, education and jobcode etc, that are linked to each employees, can assist the health care professionals to decide the type and time of medical examination and to periodically supply proper protectors. Data collected from the time of one's employment until his/her retirement can be used for the epidemiologic surveillance which will enable to evaluate the employee's health status related to his/her work environments, and to indentify the places that are necessary to be improved.