We investigated the association between the three polymorphisms of the endothelial nitric oxide synthase (eNOS) gene (single-nucleotide polymorphism (SNP); rs2070744, rs1799983, variable number tandem repeat (VNTR) in intron 4) and scores on the Hamilton Rating Scale for Depression, plasma metabolites of NO (NO(x) ) or ankle brachial index in patients with MDD and healthy controls.