During 2006, NSW and ACT Health Departments jointly engaged KPMG to develop an Operating Theatre Requirements' Projection Model and an accompanying planning guideline. A research scan was carried out to identify drivers of surgical demand, theatre capacity and theatre performance, as well as locating existing approaches to modelling operating theatre requirements for planning purposes. The project delivered a Microsoft Excel-based model for projecting future operating theatre requirements, together with an accompanying guideline for use of the model and interpretation of its outputs. It provides a valuable addition to the suite of tools available to Health staff for service and capital planning. The model operates with several limitations, largely due to being data dependent, and the state and completeness of available theatre activity data. However, the operational flexibility built into the model allows users to compensate for these limitations, on a case by case basis, when the user has access to suitable, local data. The design flexibility of the model means that updating the model as improved data become available is not difficult; resulting in revisions being able to be made quickly, and disseminated to users rapidly.