Recently, a German draft standard that describes a method to assess the performance of an operating room ventilation system has been made available by the VDI [1]. To evaluate the VDI procedure and to assess practical problems, measurements have been performed in a full-scale mock-up of an operating theatre. In the design stage the VDI approach may also be useful for an objective design assessment. In that case the approach can be mimicked through the application of the Computational Fluid Dynamics (CFD) technique. In this paper the results of the full scale measurements and a comparison with numerical results will be presented. It is possible to use the VDI 2167 to evaluate the performance of a room in a reproducible manner. The CFD simulations underestimate the temperatures in the periphery of the room. A better prediction of these temperatures will lead to a better prediction of the particle concentration on the operating table