Objectives The objective of this study was to investigate the differences in sociodemographic and clinical characteristics, temperaments, and quality of life between panic disorder (PD) patients with and without major depressive disorder (PD+MDD and PD-MDD patients, respectively). Methods We compared 411 PD-MDD and 219 PD+MDD patients. All patients who were drug-free for at least 1 month were assessed at initial outpatient visits before the administration of medication. The following instruments were used for assessment: the NEO Personality Inventory-Neuroticism (NEO-N) ; the Temperament and Character Inventory-Harm Avoidance (TCI-HA) ; the State-Trait Anxiety Inventory (STAI) ; the Intolerance of Uncertainty Scale-Short (IUS); the Anxiety Sensitivity Index-Revised (ASI-R); the Beck Depression Inventory (BDI) ; the Beck Anxiety Inventory (BAI); the Penn State Worry Questionnaire (PSWQ) ; the Generalized Anxiety Disorder for 7 item (GAD-7) ; the Albany Panic and Phobia Questionnaire (APPQ) ; the Panic Disorder Severity Scale (PDSS) ; the Early Trauma Inventory Self Report-Short Form (ETISR-SF) ; the Scale for Suicidal Ideation (SSI) ; the World Health Organization Quality of Life Scale Abbreviated Version (WHOQOL-BREF) ; the Sheehan Disability Scale (SDS) ; and the Short Form health survey (SF-36). Results Compared to the PD-MDD patients, the PD+MDD patients were younger and more likely to be unmarried. They showed higher rates of unemployment, lower levels of education and income, younger age of onset, more previous suicide attempts, a greater incidence of agoraphobia, and more previous treatments. The PD+MDD patients showed significantly higher scores on the NEO-N, the TCI-HA, the STAI, the IUS, the ASI-R, the BDI, the BAI, the PSWQ, the GAD-7, the APPQ, the PDSS, the ETISR-SF, and the SSI. In addition, the PD+MDD patients showed significantly lower quality of life than did the PD-MDD patients. In contrast with previous studies, we observed no significant differences between the two groups in terms of gender, duration until treatment, and psychiatric comorbidities. Conclusions This study showed that the PD+MDD patients have more early trauma experiences, higher levels of anxiety-related temperaments, more severe panic and depressive symptoms, and lower quality of life than the PD-MDD patients.