Catechol-O-methyltransferase (COMT) and serotonin receptor 2A (5HTR2A) polymorphisms have been investigated for their possible role in panic disorder (PD). The aim of this study was to investigate the genotype distribution of the COMT val158met and 5HTR2A 102T/C polymorphisms in PD. COMT val158met is a polymorphism at codon 158 that results in variations in COMT enzymatic activity with high-(H) and low-activity (L) alleles. The 5HTR2A 102T/C polymorphism comprises a T-to-C mutation at position 102. The effects of symptom severity, gender, and age of onset were also investigated. The participants were 105 outpatients with PD and 130 controls. The severity of the symptoms of PD was assessed by the Panic and Agoraphobia Scale (PAS). Polymorphisms of the 5HTR2A and COMT genes were identified using polymerase chain reaction and restriction fragment length polymorphism analysis. A significant relationship was found between the COMT Val158Met polymorphism and PD. No significant differences were found in genotype distributions or allele frequencies of the 5HTR2A polymorphisms between the PD and control groups. There were no significant relationships between the COMT and 5HTR2A polymorphisms and age of onset, gender, presence of agoraphobia, or PAS scores in the PD group (p > 0.05). (C) 2011 Elsevier Inc. All rights reserved.