To Determine Effect and Safety of Tadalafil Taken by Men of Different Races and With Different Diseases When Needed for Erections

An Open-Label Study to Evaluate the Efficacy and Safety of Tadalafil Administered "On Demand" to Men of Various Populations With Erectile Dysfunction

To compare men of different races and those with diabetes or depression to white men that do not have diabetes or depression but also suffer from the inability to get or keep an erection.

Inclusion Criteria:

• At least 3 months history of erectile dysfunction (ED)
• Anticipate a monogamous relationship with a female sexual partner
• Be able to make minimum required sexual intercourse attempts
• Abstain from using any other ED treatment

Exclusion Criteria:

• Other primary sexual disorders
• History of penile implant or clinically significant penile deformity
• History or current nitrate use
• History of certain heart problems
• History of certain kidney problems