Attempts to understand the underlying mechanisms of association between psychological factors and panic disorder have been mostly based on psychodynamic description. Evidence of the importance of serotonergic (5-HT) system in panic disorder (PD), however, has substanti ally increased in recent years. OBJECTIVE The objective of our study was to determine whether there was a specific personality profile of panic disorder patients and how it was related to possible neurobiological mechanisms underlying personality dimensions. PATIENTS AND METHODS Sample consisted of 14 inpatients with ICD-X diagnosis of panic disorder and 34 healthy control subjects. Personality dimensions were assessed by Minnesota Multiphasic Personality Inventory (MMPI-201) and Tridimensional Personality Questionnaire (TPQ). To assess central 5-HT function, platelet monoamine-oxidase (MAO) activity was measured. RESULTS In panic disorder group, higher scores of histrionic, depressive and hypochondriac subscales and significant increase of harm avoidance (HA) scale as well as low MAO activity were found. Negative correlation was established between MAO activity and psychopathic deviance MMPI scale. CONCLUSION The obtained results might indicate a specific personality profile of patients with panic disorder, which is characterized by high neuroticism, fearfulness, inhibition, shyness and apprehensive worry. Low MAO activity and high HA scores possibly indicate underlying hyperserotonergic state. The observed correlation between personality traits and MAO activity provide additional support for the hypothesized functional relationship between underlying central monoaminergic activity and temperament traits associated with anxiety, depression and impulsivity.