International audienceThe Nord - Pas-de-Calais region of France is under-served in terms of access to cardiovascular surgery services, as illustrated by relatively high levels of waiting list mortality. This prompted the decision to create a new surgical unit (notably with facilities for extracorporeal circulatory support) in the region's densely populated, former industrial heartland called the “Mining Basin". Geographical and epidemiological modelling was used prospectively to estimate the likely future level of activity of the existing public sector cardiovascular surgery units. Furthermore, information on the regional population distribution and the likely pattern of service use enabled us to estimate the new unit's potential activity. Our simulations produced nine scenarios which describe variations in the existing public units' activity ranging from –54% to +95%. This type of approach should enable policy makers to improve the organization of healthcare provision