Objective. Escitalopram is the most selective of the serotonin reuptake inhibitors. Methods. We review all the clinical trials (three pivotal placebo-controlled trials with citalopram as an active reference, one long-term non-inferiority study and one head-to-head superiority study) that include citalopram as an active reference in major depressive disorder (MDD), and studies that evaluate the cost-effectiveness of the two drugs. Results. In two of the pivotal studies and in the long-term study, escitalopram was numerically better than citalopram in reducing Montgomery-Asberg Depression Rating Scale (MADRS) scores from baseline, with comparative tolerability. Meta-analyses of these studies showed statistically significant differences in favour of escitalopram in terms of reducing MADRS and increasing response. This effect was particularly apparent in patients with higher baseline MADRS scores. These trends were confirmed in a head-to-head study, which clearly demonstrated the superiority of escitalopram compared with citalopram on primary and secondary endpoints. The difference between treatments was clinically relevant. Cost-effectiveness analyses demonstrated that although escitalopram has a slightly higher unit cost than generic citalopram, expected direct medical and productivity- related costs were lower with escitalopram than citalopram. Conclusion. On the basis of these results, escitalopram was concluded to be more clinically effective and more cost-effective than citalopram for the treatment of MDD, with a similar tolerability profile.