Neuroimaging studies of posttraumatic stress disorder (PTSD) have reported functional abnormalities in brain regions involved in fear conditioning, extinction, and emotion regulation. These findings have prompted researchers to consider whether PTSD can be characterized as a stress-induced fear circuitry disorder. In this review, the authors summarize the results of functional neuroimaging studies and conclude that there is a strong argument for characterizing PTSD as a stress-induced fear circuitry disorder. They also acknowledge that (a) fear is not the only emotion associated with PTSD, (b) a state of fear is not required to observe fear-circuitry abnormalities in this disorder, and (c) not all functional abnormalities in PTSD are related to fear circuitry. Implications for future diagnostic classifications are discussed.