Inclusion Criteria:

• Male and female outpatients aged 19-60 years.
• Patients will meet DSM-IV criteria for major depressive disorder as determined by the mood disorders section of the Mini International Neuropsychiatric Interview (MINI, Sheehan et al, 1998).
• A score of 20 or greater on the Hamilton Depression Rating Scale (Ham-D), indicating at least moderately severe depression.
• Competency to give informed consent.

Exclusion Criteria:

• Pregnant women, lactating women and sexually active women of childbearing potential who are not using medically accepted means of contraception.
• Serious suicidal risks as judged by the clinician and the MINI.
• The following DSM-IV diagnoses (to ensure a homogeneous diagnostic group): organic mental disorders; substance abuse/dependence, including alcohol, active within the last year; schizophrenia, paranoid, or delusional disorders; other psychotic disorders; panic disorder or generalized anxiety disorder, if a primary diagnosis; obsessive-compulsive disorder or post-traumatic stress disorder; bipolar disorder; bulimia nervosa or anorexia nervosa.
• Serious illness including cardiac, hepatic, renal, respiratory, endocrinologic, neurologic and hematologic disease that is not stabilized, or a past history of convulsions.
• Any retinal disease or systemic illness with active retinal involvement (e.g. diabetes) that precludes the use of bright light.
• Patients who have a history of severe allergies and multiple drug adverse reactions.
• Regular or current use of other psychotropic drugs, including lithium and tryptophan.
• Patients treated with beta blocking drugs.
• Hypertensive patients being treated with guanethidine, reserpine, clonidine or methyldopa (because of possible mood-altering effects of those drugs).
• Use of monoamine oxidase inhibitors within 14 days of Visit 1 (to ensure no drug interactions between fluoxetine and MAOIs), or use of heterocyclic antidepressants within 7 days of Visit 1 (to ensure adequate washout period of two weeks between stopping previous drug and start of treatment at Visit 2).
• Previous use of fluoxetine or light therapy.
• Treatment resistance in the current episode, as defined by failure (lack of clinically significant response) of two or more antidepressants given at therapeutic doses for at least 6 weeks.
• Patients who start formal psychotherapy (e.g. cognitive-behavioural or interpersonal psychotherapy) within 3 months of Visit 1, or who plan to initiate such psychotherapy during this study.
• Patients involved in any other form of treatment for depression.