The four main aspects of applied medical information technology, which change the traditional systems of the entire health service are signal and data processing, digital modelling and interface optimisation. The information technology serving individual clinical specialties including clinical histopathology is changing at each of the four levels resulting in transformation of the communication paradigms. The object of investigation in histopathology is the digital slide, which is accessible throughout the world with no time or geographical limits. It permits the digital modelling of routine histological and/or cytological slide and it also allows measurements by using image analysis or stereology software packages. The electronic slide can be viewed, examined and diagnosed on a computer connected to a microscope, a new interface in diagnostic histopathology. This study describes the main theoretical and practical aspects, including challenges, of digital pathology and it also discusses the conditions required for successful information management. It reviews the experiences of the last one and half decades gained in the field of pathological information technology in Hungary including its main episodes and milestones of development. Introducing its present state, this paper describes the concept and the mode of investigation of the digital slide. It shows the development and use of a virtual microscope in Hungary. Based on know-how including the British experience this review describes the possible uses of digital slides, which by improving communication could have a positive effect on the entire health care system. It summarises the possible and necessary components of a digital pathology laboratory, which may include the new Slide Archive and Communication System (SACS). Using experimental data it mentions the possibility of generating primary digital pathological sample and producing the so called optical biopsy with no need for removing tissue from the patient.