The study will assess efficacy, safety and tolerability of 0.5 mg/day and 1 mg/day of sublingual (under the tongue) formulation of agomelatine in patients with Major Depressive Disorder. This study includes an 8-week double-blind phase.

Inclusion Criteria:

• Patients with diagnosis of MDD, single or recurrent episode, according to DSM-IV criteria.
• Current episode ≥4 weeks.
• CGI-Severity score ≥4 at Screening and Baseline.

Exclusion Criteria:

• History of bipolar disorder (I or II), schizophrenia, schizoaffective disorder, eating disorder (current or during previous one year), obsessive-compulsive disorder.
• Any other current Axis I disorder other than MDD which is the focus of treatment.
• Substance or alcohol abuse in the last 30 days, dependence in the last 6 months.
• Concomitant psychotropic medication, including herbal preparations and melatonin.
• Psychotherapy of any type.
• Prior exposure to agomelatine.
• Female patients of childbearing potential who are not using effective contraception.

Other protocol-defined inclusion/exclusion criteria may apply