The purpose of this study is to assess the efficacy, safety and tolerability of GW679769 patients with Major depressive Disorder (MDD).

Inclusion criteria:

• Primary diagnosis of Major depressive Disorder as defined in DSM-IV.
• Capable of giving informed consent and willing to comply with the study requirements.
• Women of childbearing potential must agree to one of a number of defined acceptable methods of birth control.

Exclusion Criteria:

• Primary diagnosis within the past 6 months of another Axis 1 disorder such as an anxiety disorder.
• Use of medications for a psychiatric condition including herbals in the past 2-12 weeks according to medication type.
• Subjects who, in the investigator's judgement, pose a current, serious suicidal or homicidal risk or have made a suicide attempt within the past 6 months.
• Subjects who currently meet or who met within 6 months prior to screening DSM-IV criteria for substance abuse or subjects who currently meet or who met within 6 months prior to screening DSM-IV criteria for substance dependence (other than nicotine).
• Significantly abnormal blood or urine laboratory tests or electrocardiogram (ECG).

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.