Dysregulation of hypothalamic-pituitary-adrenal axis (HPA) is seen in numerous mental disorders. Data of HPA axis disturbance in panic disorder are inconsistent. In panic disorder HPA axis hyperactivity has been observed with elevated cortisol levels. However, hypocortisolism has also been noted. Salivary cortisol as a biomarker of HPA-axis activity has received special attention. The aim of this paper is to review the findings on cortisol levels in panic disorder.