Study to Determine Safety and Effectiveness of Tadalafil on Prostate Related Sex Organ/Urinary Tract Problems

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.