Information systems for medical data storing, managing and retrieving are specific, because of the data that has different in-between associations. This data consists of text and multimedia. The purpose of this work is to propose and develop a medical data system, which uses object oriented data base. The user could store various medical data and perform data mining by selecting desirable criterions. After analysis of object-oriented technologies, were chosen object-oriented programming environment and object-oriented data base management system. For its implementation, the suitable technologies were analyzed, according to the specifics of medical data. The advantages of these technologies where shown by an experiment. Developed information system is functional and flexible enough to work with evolving medical data.