Previous studies suggested that antidepressants augmented with second-generation antipsychotics (SGAs), including aripiprazole, olanzapine, quetiapine, and risperidone, resulted in better treatment response or higher rates of remission in patients with major depressive disorder (MDD). However, population-based study on SGA augmentation for patients with MDD remains limited. The purpose of this study was to investigate the effectiveness of SGA augmentation for treatment of MDD using the National Health Insurance Research Database in Taiwan. The subjects were patients with MDD (ICD-9-CM code: 296.2 and 296.3) who were initially admitted to psychiatric inpatient settings for the first time between January 1, 1996, and December 31, 2007, and could be tracked until December 31, 2011. To assess the treatment effect of SGA augmentation, 993 MDD patients who received aripiprazole, olanzapine, quetiapine, or risperidone augmentation treatment for 8 weeks or more were included in this 1-year mirror-image study. Outcome measures included length of psychiatric hospitalization and number of psychiatric admissions and emergency room (ER) visits. After patients received SGA augmentation treatment, key psychiatric service use (including length of psychiatric hospitalization [P < .0001], number of psychiatric admissions [P < .0001], and ER visits [P = .0006]) due to MDD diagnosis was significantly reduced. Subgrouping analysis for each SGA drug also showed significant reduction in number of psychiatric admissions for MDD patients who received aripiprazole (P < .0001), olanzapine (P = .003), quetiapine (P < .0001), and risperidone (P < .0001). The study provides support that aripiprazole, olanzapine, quetiapine, and risperidone augmentation therapy could be effective in reducing psychiatric service utilization among MDD patients.