Medically unexplained symptoms (MUS) are frequently associated with a history of traumatization. The first purpose of the present review paper was to investigate systematically the evidence for such relation in a subset of clinical samples with MUS presenting with functional somatization: chronic pelvic pain, irritable bowel syndrome and conversion and somatization disorder. The second purpose was to critically review three dominant models explaining the relation between trauma and MUS (i.e. dissociation, conversion and hierarchical cognitive models). The latter model in particular adequately accounts for the non-volitional and non-intentional character of MUS and explains how traumata can affect the development of MUS without assuming that previous trauma is a necessary prerequisite of MUS. The cognitive model, however, lacks integration with current neurobiological findings, indicative of central stress-and central nervous system alterations in MUS. The final purpose of the present paper was, therefore, to review current neurobiological studies focused on trauma and MUS and to formulate a research agenda to integrate these neurobiological developments with cognitive models for MUS.