Vezin samplers are used to take a small fraction of a stream of material which is intended to be representative of all the material. Discrete Element Modelling (DEM) is used to investigate the effects of design, operating and material property factors on the extraction ratio and sample properties and to understand the mechanisms that can lead to sample bias when using a Vezin. This modelling suggests that this type of sampler performs very well giving a very good extraction ratio and negligible sample bias over a wide range of conditions. (C) 2011 Published by Elsevier Ltd.