Study to look at safety and effectiveness of different doses of tadalafil on prostate related genital/urinary tract problems.

Inclusion Criteria:

• 6 month history of lower urinary tract symptoms either obstructive and/or irritative secondary to prostate related problems as diagnosed by a urologist.
• Stopped using treatments at least four weeks prior to study and agree to not use any other treatments during the study.
• Meet required prostate symptom score and urine flow rate.

Exclusion Criteria:

• Serum prostate specific antigen (PSA) greater than 10 (between 4 and 10, inclusive, without a negative biopsy w/in the last 6 months.
• Prostate removal and various other pelvic surgeries.
• Neurological disease or condition known to affect the bladder.
• Clinical evidence of prostate cancer, urinary tract inflammation or infection, including prostatitis.
• Have taken medications such as nitrates, finasteride, or dutasteride within the year.