Antidepressants that enhance both serotonergic and noradrenergic neurotransmission may be more effective than selective serotonin reuptake inhibitors (SSRIs) for acute-phase therapy of major depressive disorder. Mirtazapine in particular has been suggested to have a faster onset of action than reuptake inhibitors. The aim of this study is to compare the remission rates and time to remission in patients with major depression taking either mirtazapine or an SSRI in an all-inclusive set of studies. Data were obtained from all eligible randomized controlled studies contrasting mirtazapine and SSRIs. Meta-analyses of remission rates and time to remission, together with a supportive analysis of mean change from baseline Hamilton Depression Rating Scales-17 were performed, using individual patient data from 15 randomized controlled trials of mirtazapine (N = 1484) versus various SSRIs (N = 1487) across 6 weeks of double-blind therapy. Analyses were repeated for the eight studies that lasted at least 8 weeks. Remission rates for patients treated with mirtazapine were significantly higher when compared with those treated with an SSRI after 1 (3.4 vs. 1.6%, P = 0.0017), 2 (13.0 vs. 7.8%, P<0.0001), 4 (33.1 vs. 25.1%, P<0.0001), and 6 weeks (43.4 vs. 37.5%, P = 0.0006) of treatment. Mirtazapine-treated patients had a 74% higher likelihood of achieving remission during the first 2 weeks of therapy compared with patients treated with SSRIs. In conclusion, the findings indicate that mirtazapine may be a more rapidly effective antidepressant than SSRIs.