Grid computing is a new technology enhancing services already offered by the Internet offering rapid computation, large-scale data storage, and flexible collaboration by harnessing together the power of a large number of commodity computers or clusters of basic machines. The grid has been used in a number of ambitious medical and healthcare applications. While these have been restricted to the research domain, there is a great deal of interest in real applications. There is some tension between the spirit of the grid paradigm and the requirements of healthcare applications. The grid maximises its flexibility and minimises its overheads by requesting computations to be carried out at the most appropriate node in the network; it stores data at the most convenient node according to performance criteria. A healthcare organization is required to maintain control of its patient data and be accountable for its use at all times. Despite this apparent conflict, certain characteristics of grids help to resolve the problem: “grid services” may provide a solution by negotiating ethical, legal, and regulatory compliance according to agreed policy.