Objective: Selective serotonin reuptake inhibitors (SSRIs) are the cornerstone of treatment of major depressive disorder (MDD). However, non-response is common, often necessitating combination strategies. The present study assessed the efficacy of vortioxetine as an add-on therapy in patients with SSRI-resistant MDD. Methods: The charts of 36 adult outpatients with DSM-IV-TR MDD who had not achieved a response after at least 8 weeks of treatment with an SSRI were reviewed retrospectively. Subjects were treated with vortioxetine (5-20 mg/day) for 8 weeks added to the current SSRI. The main outcome measures were change from baseline in total Hamilton Scale for Depression (HAM-D) score and the rate of response (a 50% or greater reduction in HAM-D score and a Clinical Global Impression ‐ Improvement module [CGI-I] score of 1 or 2 at endpoint). HAM-D scores ≤ 7 were considered as remission. Additional outcome measures included the Snaith-Hamilton Pleasure Scale (SHAPS) and the Scale for Suicide Ideation (SSI). Results: 32 patients completed the 8 weeks of treatment. At 8 weeks, a significant reduction in HAM-D score was observed (p ≤ 0.001), with response obtained by 41.7% and remission by 33.3% of patients. Significant reductions in SHAPS and SSI were also observed (p ≤ 0.001 for both scales). Conclusions: Adjunctive vortioxetine may be useful and well-tolerated in stage I treatment-resistant depression. However, the limitations of this study (such as small sample size, absence of randomization and control group, retrospective design, etc.) must be considered.