Inclusion Criteria:

• Erectile dysfunction for more than 6 months according to the NIH Consensus statement (the inability to attain and maintain erection of the penis sufficient to permit satisfactory sexual intercourse).
• Stable, heterosexual relationship for more than 6 months.
• Diagnosis of mild Major Depressive Disorder using a structured interview (SCID-1 or MINI), according to DSM-IV criteria. Before randomization, a psychiatrist must interview the subject at Visit 2 to validate both the diagnosis of MDD and the subject's continuation in the study without the need for anti-depressant medication or psychotherapy).
• Patients must score greater than 13 on the CES-D at Visit 1.
• Patients must score between 11 and 17 on the 17-item HAM-D at Visit 1 and Visit 2.
• The patient must make at least four attempts at sexual intercourse on four separate days during the untreated baseline period
• At least 50% of the attempts of sexual intercourse during the untreated baseline period have to be unsuccessful

Exclusion Criteria:

Previous or Current Medical Conditions

• Any unstable medical condition or substance abuse disorder that, in the opinion of the Investigator, is likely to affect the patient's ability to complete the study or precludes the patient's participation in the study.
• Patients who score > 0 on item #3 on the HAM-D17 or men who, in the investigator's judgement, pose a current serious suicidal or homicidal risk or have made a suicide attempt within the past 12 months.
• Men with a current (or within 6 months prior to screening) Axis 1 disorder other than MDD (major depressive disorder). Patients with a history, or who currently meet the DSM-IV criteria, of Bipolar Disorder, Schizophrenia, Schizoaffective Disorder, Delusional (Paranoid) Disorder, Panic Disorder, Post-Traumatic Stress Disorder. Patients with a Personality Disorder are excluded if, in the investigator's opinion, it will interfere with the conduct of the trial.
• Retinitis pigmentosa.
• Unstable angina pectoris.
• History of radical prostatectomy.
• History of myocardial infarction, stroke, electrocardiographic ischemia (except stable angina), or life-threatening arrhythmia within the prior 6 months.

Abnormal Laboratory Values

• AST or ALT > 3 times the upper limit of normal Concomitant Medications
• Patients who are taking nitrates or nitric oxide donors (e.g., molsidomine, minoxidil). Topical minoxidil is permitted.
• Patients who are taking androgens (e.g., testosterone) or anti-androgens.
• Patients taking trazodone, or any other anti-depressant including monoamine oxidase inhibitors, St. John's Wort, SSRIs or tricyclic anti-depressants are excluded, or use of these medications in the last 2 weeks before Visit 1. Fluoxetine is excluded in the last 4 weeks before Visit 1.
• Patients who are taking the following potent inhibitors of cytochrome P 450 3A4: the HIV protease inhibitors ritonavir and indinavir, erythromycin or the anti-mycotic agents itraconazole and ketoconazole (topical forms are allowed).
• Subjects who are taking alpha-blockers.
• Use of any therapy for erectile dysfunction within seven days of Visit 1 and during the trial.
• Patients who require, or are likely to require, treatment with psychotherapy or psychotropic drugs during the course of the study. Men receiving formal individual psychotherapy for depression currently or in the 12 weeks prior to screening visit.

Abnormal Laboratory Values

• Patients who have a serum total testosterone level >10% below the lower limit of normal (according to the range specified by the responsible laboratory).

Other Exclusions

• Patients whose urine screen for substances of abuse is positive.
• Patients unwilling to refrain from consuming grapefruit juice or products containing grapefruit juice with study medication.