This is a placebo-controlled, fixed dose study that will evaluate the efficacy and safety of GW679769 in subjects with major depressive disorder.

Inclusion criteria:

• Subjects must have the ability to comprehend the key components of the consent form.
• Subject must have met DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision) criteria for current MDE (major depressive episode) for at least 8 weeks prior to the Screening Visit.
• If female, subjects must be practicing an acceptable method of birth control.
• Subjects must have rating scores as outlined.

Exclusion criteria:

• Subjects whose symptoms of the MDE are better accounted for by another diagnosis.
• Subjects with a history of schizophrenia, schizoaffective disorders or bipolar disorder.
• Subjects have a positive urine test for illicit drug use and/or a history of substance abuse or alcohol dependence within the past 12 months.
• Subjects with an unstable medical disorder.
• If female, pregnant or lactating.
• Subjects who have received ECT (electroconvulsive therapy) or TMS (transcranial magnetic stimulation) within the 6 months preceding screening or who have ever been homicidal.