Brain-derived neurotrophic factor (BDNF) has been studied extensively in relation to the susceptibility to mood disorders (MD), although it remains to be clarified whether BDNF is a susceptibility locus for MD phenotypes, including therapeutic response to antidepressants. We have performed a single-marker and haplotype association study of eight TagSNPs polymorphisms in the genomic region containing the BDNF gene in 342 control subjects and 374 patients with MD, and have tested the association with antidepressant treatment outcome. None of the eight single nucleotide polymorphisms (TagSNPs) was significantly associated with MD phenotype after Bonferroni correction. In the single-marker analysis, a SNP was found to be associated with the patient's state of 'remitter' after adequate trial with a single antidepressant phenotype (odds ratio (OR)=2.95; P=0.0025). We also identified a haplotype associated with this phenotype. This study supports the implication of BDNF in antidepressant treatment outcome in MD, with specific association with 5' upstream region of BDNF gene.