To probe the hypothesis of a role for a functionally relevant 44 hp insertion/deletion of the serotonin transporter promoter in the aetiopathogenesis of panic disorder, we determined the allele frequency of the variant in two samples (combined n = 158) of panic disorder patients (DSMIII-R) and compared it with its allele frequency in two ethnically matched control samples (combined n = 169). The fact that no difference could be observed (χ2 analysis) argues against a major role for this serotonin transporter promoter polymorphism in the aetiopathogenesis of panic disorder.