This paper provides a brief review of the developments in neurobiological research of posttraumatic stress disorder (ptsd), particularly into the link between the disorder and the central and peripheral stress-regulating processes. ptsd is an impairment of neuronal circuits and stress-regulating systems in the brain, where a critical note is played by limbic structures such as the hippocampus, the amygdala and the medial prefrontal cortex. In patients with ptsd the 'behaviour' of these neuronal circuits and systems is chronically disturbed. Characteristic symptoms are increased stress reactivity, reduction of declarative memory performance, high emotionality in response to trauma-related stimuli and over-representation of traumatic memory, all of which can be described as chronic dysregulated processes. Because of improvements in research designs and stratification of research populations, the specificity of research findings has improved and the developmental trajectories of specific ptsd parameters have been described more clearly. One of the most promising developments in the field of research designs is the current shift away from cross-sectional research designs to 'true prospective' research designs.