The use of tritium as a basic fuel material in a thermonuclear fusion reactor raises particular safety issues due to the combined effects of its physicochemical properties and its radioactive nature. Furthermore, the possibility of attaining further significant progress in developing and demonstrating the feasibility of tritium burning devices relies on the handling of tritium macroquantities, say tens of grams, in a safe and reliable manner. It is also certain that, apart from technological constraints, any validation and exploitation of thermonuclear fusion as a source of energy will be strongly conditioned by the application of stringent operational and environmental safety criteria derived from the norms of modern legislation and public acceptance considerations. This publication illustrates the most prominent safety aspects associated with the safe operation, maintenance and experimental utilization of a tritium handling facility. Besides the need for safe and reliable systems for tritium containment, monitoring and storage, particular attention is devoted to problems linked with tritium--material interaction and tritium processing, according to the different options applicable both to the tritium handling laboratory and future fusion devices. Selected topics, such as biological hazard, dosimetry, radiological protection and environmental safety are reviewed with particular attention to implications for operators and general public. Finally, outstanding experience gained during the recent JET operation and after many years of dismantling tritiated facilities at CEN--Valduc are illustrated. The book is principally addressed to scientists concerned with tritium R&D activities, as well as to designers and operators of tritium handling plants.