In order to analyse asymmetries between hemimandibles, a sample of 24 mandibles from ferrets was studied by means of geometric morphometric methods, using a set of 3 landmarks and 14 semilandmarks, on the lateral aspect. Results showed that both size and shape played a significative role in mandibular asymmetry. For shape, there appeared significative fluctuating and directional asymmetries, with an especially high level for this latter. Landmarks corresponding to muscular attachments showed greater landmark asymmetry. This it is supported the hypothesis of a chewing side preference, e.g., a mastication-related driver for mandibular shape asymmetry.