The paper discusses continuum and discontinuum modelling in tunnel engineering. A brief review of fundamentals is presented in connection with the use of closed-form solutions and computer based numerical methods. A few remarks are derived on the choice of either continuum or discontinuum modelling of rock mass behaviour at the design analysis stage. Consideration is given to the validation of discontinuum modelling in connection with rock mass classification methods and expected tunnel response to excavation. A case study of a TBM tunnel (4.75 m diameter) in quartzitic micaschists is discussed in detail by paying attention to a comparison of modelling methods - including continuum and discontinuum modeling - applied at a fault zone.