The article reviews the neurocircuitry underlying anxiety disorders, focusing on the amygdala, medial prefrontal cortex (mPFC), hippocampus, and insular cortex. Recent neuroimaging studies have highlighted heightened amygdala activation in response to disorder-relevant stimuli in post-traumatic stress disorder (PTSD), social phobia, and specific phobia. The insular cortex also shows heightened activation in many anxiety disorders. In contrast, PTSD is associated with diminished responsivity in the rostral anterior cingulate cortex (rACC) and adjacent ventral medial prefrontal cortex (vmPFC). The review discusses the limitations of current neuroimaging studies and suggests future directions, including clarifying the roles of each component of the fear circuitry in anxiety disorders, determining whether functional abnormalities are acquired signs or vulnerability factors, linking neuroimaging findings with neurochemistry, and using neuroimaging to predict treatment response and assess treatment-related changes in brain function. The article also explores the overlap between the neurocircuitry of fear and stress responses, highlighting the interaction between the limbic-hypothalamic-pituitary-adrenal (LHPA) axis and anxiety/fear neurocircuitry. Finally, it provides a detailed review of the neurocircuitry abnormalities in PTSD and panic disorder, including amygdala hyperactivity, vmPFC hyporesponsivity, and hippocampal dysfunction.The article reviews the neurocircuitry underlying anxiety disorders, focusing on the amygdala, medial prefrontal cortex (mPFC), hippocampus, and insular cortex. Recent neuroimaging studies have highlighted heightened amygdala activation in response to disorder-relevant stimuli in post-traumatic stress disorder (PTSD), social phobia, and specific phobia. The insular cortex also shows heightened activation in many anxiety disorders. In contrast, PTSD is associated with diminished responsivity in the rostral anterior cingulate cortex (rACC) and adjacent ventral medial prefrontal cortex (vmPFC). The review discusses the limitations of current neuroimaging studies and suggests future directions, including clarifying the roles of each component of the fear circuitry in anxiety disorders, determining whether functional abnormalities are acquired signs or vulnerability factors, linking neuroimaging findings with neurochemistry, and using neuroimaging to predict treatment response and assess treatment-related changes in brain function. The article also explores the overlap between the neurocircuitry of fear and stress responses, highlighting the interaction between the limbic-hypothalamic-pituitary-adrenal (LHPA) axis and anxiety/fear neurocircuitry. Finally, it provides a detailed review of the neurocircuitry abnormalities in PTSD and panic disorder, including amygdala hyperactivity, vmPFC hyporesponsivity, and hippocampal dysfunction.