Effect of Tadalafil Once a Day in Men With Erectile Dysfunction

Inclusion Criteria:

• You are male and aged at least 18 years.

• Have a history of erectile dysfunction (ED)(defined as the consistent inability toachieve and/or maintain an erection sufficient to permit satisfactory sexualintercourse) of at least 3 months duration.

• Agree not to use any other treatment for ED, including herbal and over-the-counter (OTC) medications, during the study

• You agree to make at least four sexual intercourse attempts with the female sexualstudy partner during the 4-week run-in period without medication

• Your entry laboratory test results and medical tests meet study requirements

• You agree to use the study drug only as instructed by your study doctor and staff andto return any unused study drug and containers at the end of the study or as otherwiseinstructed by the study doctor.

• If currently using cholesterol lowering medications (for example: statins) ormedications to lower blood pressure (example: angiotensin-converting enzyme (ACE)inhibitors or calcium channel blocker medications), you need to be on a stable doseand you and your study doctor do not expect any dose change during the study.

Exclusion Criteria:

• You have received previous or current treatment with tadalafil or any other PDE5inhibitor.

• Currently receives treatment with doxazosin, nitrates, cancer chemotherapy, oranti-androgens (except finasteride e.g. Propecia™ or Proscar®, or dutasteride e.g.Avodart®).

• You have had significant heart disease as determined by your doctor in charge of thisstudy or a member of the doctor's staff.

• Have a history of significant central nervous system injuries (including stroke orspinal cord injury) within the last 6 months.

• Have a history of loss of vision in one eye because of nonarteritic anterior ischemicoptic neuropathy (NAION), regardless of whether this episode was in connection or notwith previous PDE5 inhibitor exposure.