Objective: The application of an electronic slide and a software simulated virtual microscope can contribute to a more efficient, convenient histological analysis. These techniques would also support the automation of histological analysis and three dimensional reconstruction of histological objects. Study Design: A fully computer controlled microscope (Axioplan 2 MOT), video camera (Grundig FAC 830) and an Intel Pentium II based PC were used for the development of the electronic slide. The applied frame grabber had 640 X 560 resolution, 64 kb color depth. A program was developed, called Pyramid, for the scanning of an entire slide. Autofocusing, image reduction and frame joining algorithms were implemented in the virtual microscope application. Results: The autofocusing and digitization of one image segment (400X magnification, 0,0725 mm2) took 8 seconds. The harddisk volume of one frame is between 60 and 100 kilobytes (kb) after JPEG compression. The overall harddisk place for a gastric biopsy is around 130 - 150 megabytes. The Pyramid program contains routines for electronic evaluation of the slide. The major microscopic functions are implemented: moving in any free directions in discrete or continuous steps, magnifications on a discrete scale (400, 200, 100X), and in continuous scale. Up to 1o notes can be placed on any place of the slide and can be retrieved within a second. The program can be used in local area networks for slide evaluations. Conclusions: The scanning speed is now too low for routine application, however with further developments in data storage and imaging technology, the electronic slide and the virtual microscope can be alternative techniques in the computerization of the histology laboratory. After the scanning of consecutive sections and a mathematical matching procedure supracellular organizations from gastric biopsies were reconstructed giving new insight into tumor growth.