Escitalopram is an effective, well-tolerated treatment for major depressive disorder in both primary and specialist settings. This analysis compared the efficacy of escitalopram with citalopram in the treatment of patients with severe depression [defined as a score of > or =30 Montgomery-Asberg Depression Rating Scale (MADRS)]. Data from three clinical trials were used for this pooled analysis. A total of 506 severely depressed patients were included (169 received escitalopram, 171 citalopram and 166 placebo). Mean change from baseline in MADRS total scores (primary efficacy parameter) was significantly higher in the escitalopram-treated group compared with the citalopram-treated group (p = 0.003). There was a significant difference in response between escitalopram and citalopram (56 vs. 41%, respectively, p = 0.007). Results from secondary efficacy parameters (Hamilton rating for depression and Clinical Global Impression of Improvement and Severity scales) were consistent with previous results. The benefits in severe depression of escitalopram vs. citalopram were so demonstrated.