Introduction. A number of theoretical models have identified dissociation as a possible cognitive mechanism underlying medically unexplained symptoms (''hysteria''). A review of research and theory in this area indicates that the dissociation concept is a useful explanation of this phenomenon. However, existing models of dissociation have a number of explanatory shortcomings. Methods. This article describes a recent model of unexplained illness that aims to extend the dissociation concept by reference to research and theory from contemporary cognitive psychology. Results. According to this view, unexplained symptoms should be regarded as disturbances of consciousness and behavioural control, resulting from the chronic activation of stored symptom representations within memory. This process is driven by the repeated reallocation of high-level attention on to symptom representations. Conclusions. The model offers a fresh perspective on the nature of unexplained symptoms, providing an explicit account of the factors involved in the creation and maintenance of this phenomenon.