This paper presents a specific modelling system which simulates the commodity, delivery and vehicle goods movements, developed in order to support ex-ante assessment of city logistics measures. A review of models developed to simulate the urban freight transport demand is also reported. The review analysis highlights the limits of models for the ex-ante assessment of city logistics measures. For this reason this paper proposes a new modelling system made of different steps approaching problems related to: quantity OD flows, service-type OD flows, delivery OD flows, delivery OD flows for delivery time and vehicle type, and vehicle OD flows. This modelling system has been specified and calibrated using some surveys carried out in the inner area of Rome, where more than 500 truck drivers and more than 600 retailers have been interviewed.