Grid technology has enabled clustering and access to, and interaction among, a wide variety of geographically distributed resources such as supercomputers, storage systems, data sources, instruments as well as special devices and services, realizing network-centric operations. Their main applications include large scale computational and data intensive problems in science and engineering. Grids are likely to have a deep impact on health related applications. Moreover, they seem to be suitable for tissue-based diagnosis. They offer a powerful tool to deal with current challenges in many biomedical domains involving complex anatomical and physiological modeling of structures from images or large image databases assembling and analysis. This chapter analyzes the general structures and functions of a Grid environment implemented for tissue-based diagnosis on digital images. Moreover, it presents a Grid middleware implemented by the authors for diagnostic pathology applications. The chapter is a review of the work done as part of the European COST project EUROTELEPATH.