The aim of the present observational study is to assess the clinical response, functional impairment and quality of life in outpatients with Major Depressive Disorder who demonstrated an initial positive response to the acute treatment with Trazodone once-a-day monotherapy, for up to 24 weeks.

This is an observational, prospective, single group, multicentre, international study.

The present study is planned to assess, in a real-world setting, the long-term clinical response, functional impairment and quality of life in outpatients with Major Depressive Disorder who, according to the physician's judgment, have responded to the acute monotherapy (6 to 8 weeks of treatment) with Trazodone once-a-day and are eligible to continue Trazodone once-a-day monotherapy according to clinical practice.

Inclusion Criteria:

Male and female patients of any ethnic origin ≥18 years old at Baseline. Outpatients who meet the Diagnostic and Statistical Manual of Mental Disorders (DSM)-5 or the International Classification of Diseases (ICD)-10 criteria for MDD as their primary diagnosis and presenting with an episode of MDD.

Patients judged as responders to the acute monotherapy with TzOAD after a minimum of 6 and a maximum of 8 weeks of treatment and who are eligible to continue the assigned monotherapy according to the physician's judgement.

Patients legally capable of giving their written consent for participation in the study and for personal data processing and willing to comply with all study procedures.

Exclusion Criteria:

Patients that meet any of the contraindications to the administration of TzOAD according to the approved SmPC.

Patients with previous or current diagnosis of bipolar disorder, schizophrenia or other psychotic disorder, dysthymic or adjustment disorders, mental retardation, organic mental disorders or mental disorders due to a general medical condition.

Patients with previous or current history of a clinically significant neurological disorder, or any neurodegenerative diseases that might compromise the participation in the study.

Patients who are, according to the physician's judgement, at serious risk of suicide.

Patients with substance abuse or dependence (except nicotine dependence), as defined by DSM-5.

Patients participating in any pharmacological or non-pharmacological interventional study.

Outpatients presenting with Major Depressive Disorder who, following an initial positive response to the acute treatment with Trazodone once-a-day monotherapy, will be eligible according to the physician's judgement, to enter the continuation therapy and will be observed up to 24 weeks.