This chapter introduces this important subject and the topic of risk management. Tunnelling has become recognised as an environmentally friendly way of providing road and rail capacity in an increasingly congested world. Tunnels are high value assets both in terms of their intrinsic worth and their value within the national infrastructure. All the health and safety hazards of normal civil engineering construction can be found in tunnelling along with a few which are specific to tunnelling. Occupational health and safety in tunnelling is normally subject to the same legislation as surface construction. Over the past three decades, a considerable amount of legislation aimed at establishing common standards of occupational health and safety has emanated from the European Parliament. Clients and designers, as well as contractors, have a contribution to make in ensuring good health and safety performance in tunnelling, and their responsibilities are set down in legislation and guidance in many countries.