The efficacy of antidepressants to treat major depressive disorder (MDD) varies by patient characteristics. This post-hoc analysis evaluated the effects of vilazodone across patient subgroups in adults with MDD. Data were pooled from four trials of vilazodone (NCT00285376, NCT00683592, NCT01473394, and NCT01473381). Mean change from baseline to week 8 in Montgomery-Åsberg Depression Rating Scale (MADRS) total score, MADRS response (≥50% total score improvement), and MADRS remission (total score≤10) were analyzed in the pooled intent-to-treat population (vilazodone=1254, placebo=964) and in subgroups of patients categorized by sex, age, MDD duration, recurrent episodes, baseline MADRS total score, and current episode duration. MADRS total score improvement was significantly greater with vilazodone versus placebo in the intent-to-treat population and in all patient subgroups (P<0.001). MADRS response and remission rates significantly separated from placebo (P<0.05) regardless of age, sex, MDD duration, recurrent MDD, and baseline symptom severity [except remission in patients with very severe baseline symptoms (MADRS score≥35)] and in patients with a shorter current episode duration (≤12 months). Despite the limitations associated with analyzing uncommon outcomes (e.g. MADRS remission) in small subgroups, vilazodone was an effective treatment in multiple patient populations, including those where reduced efficacy has previously been reported: males, older individuals, patients with a longer duration of MDD, and patients with recurrent depression.