Vilazodone (Viibryd(®)) exhibits the combined properties of a selective serotonin reuptake inhibitor (SSRI) and a serotonin 5-HT1A receptor partial agonist, and is approved in the US for the treatment of major depressive disorder (MDD) in adults. In four randomized, double-blind, clinical trials, oral vilazodone 20 or 40 mg once daily for 8 or 10 weeks reduced from baseline (improved) the Montgomery-Åsberg Depression Rating Scale (MADRS) total score significantly more than placebo in adult patients with MDD. In these trials, significantly greater reductions in MADRS total score with vilazodone compared with placebo were seen from either week 1, week 2 (two trials) or week 6. In a noncomparative study, MADRS total scores continued to improve throughout therapy for up to 1 year. Vilazodone was generally well tolerated, with the most common treatment-emergent adverse events being mild or moderate diarrhoea, nausea and headache. Vilazodone had only limited adverse effects on sexual function or bodyweight. Therefore, vilazodone is an effective agent for treating MDD in adults.