Panic disorder is a highly prevalent mental disease characterized by sudden and recurrent panic attacks. Studies on patients with panic disorder have found dysfunctional strategic processing of facial expressions and abnormal automatic processing of panic-related stimuli. However, whether the automatic processing of facial emotions in patients with panic disorder is normal is unknown. Visual mismatch negativity (vMMN) reflects automatic processing of change detection. We recorded expression-related vMMN to compare the automatic detection of schematic facial emotions (negative and positive) of 12 patients with panic disorder and 17 age-matched and education-matched controls. During the late time window (220-330 ms), the vMMN amplitudes for two emotions (negative and positive) were significantly decreased in patients with panic disorder (P=0.02). This finding implies that the ability to automatically detect facial emotions is impaired in patients with panic disorder. This is the first report on expression-related vMMN being used with patients with panic disorder.