The objectives of this study were to: (1) to assess the risk of erectile dysfunction (as treatment with PDE-5 inhibitors) in males with and without a history of treatment with serotonergic antidepressants, in the absence of medical or psychiatric comorbidities or other medications associated with ED, and (2) to estimate the prevalence of post-SSRI sexual dysfunction (PSSD) in males, as evidenced by treatment-emergent ED treated with PDE-5 inhibitors persisting after discontinuation of antidepressant treatment and no active diagnosis of depression or anxiety. This evidence concerns the gene PDE5A and major depressive disorder.