Available data on gamma amino butyric acid (GABA) support the hypothesis that a dysfunction in the brain GABAergic system activity contributes to vulnerability to affective disorders (AD), including bipolar disorder (BPAD) and unipolar disorder (UPAD). The localization of the alpha3 subunit GABA receptor (GABRA3) gene in Xq28, a region of interest for BPAD suggests that GABRA3 may be a relevant candidate gene. In the present study, we tested the genetic contribution of the GABRA3 dinucleotide polymorphism in a European multicentre UPAD case-control sample [UPAD (n = 106), controls (n = 212)]. Our negative results suggest that GABRA3 does not confer susceptibility nor is it in linkage disequilibrium with another close gene involved in the genetic aetiology of UPAD.