The purpose of this research was to develop an information system for diagnostic tests regarding their purpose, method. and notification, and to provide people in the field with easy access to information by using CD-ROM title or data communication. The Joint Application Design Method which is popular in developing information systems was used. First the user requirements for the target system were gathered and analyzed through a survey of patient and nurses in a number of hospitals. Thus. the functions which were to be included were analyzed in details. A list containing all the required tests and their content was defined to be used as the database in the system. Focusing on making the searching procedure easy to use. the researchers defined the input and the output of the system to have for a user-friendly user interface. Searching functions using not only, a name of the test category or a test name itself, but also a disease name were added. Furthermore, the function of maintaining an updated database in an efficient way was also included. This system is useful in that it provides an efficient and effective way to search for any necessary information about diagnostic tests and an easy way to keep the updated database. Based on user and system requirement analysis. user-friendly interface. and the well-defined database. all of which were designed and implemented in this research. it is expected that an Internet-based diagnostic test information system can be developed in a near future.