Comparison of Finasteride and Tamsulosin for Treatment of Benign Prostatic Hyperplasia (BPH) (MK-0906A-149 AM2)

Inclusion Criteria: * Possess a clinical diagnosis of BPH. * Able to read, understand, and complete the study questionnaire. Exclusion Criteria: * History or recurrent evidence of any condition, therapy, lab abnormality or other circumstance that might confound the results of the study, or interfere with participation for the full duration of the study. * History of malignancy ≤ 5 years prior to signing informed consent, except for adequately treated basal cell or squamous cell skin cancer, including prostate cancer of any duration, evidence or suspicion of prostate cancer on a previous biopsy. * History of prostatic surgery or other invasive procedures to treat BPH or history of bladder neck obstruction, bladder cancer, and/or pelvic irradiation, urinary incontinence, recurrent urinary tract infection, urethral stricture, or bacterial prostatitis. * History of acute urinary retention (ie, inability to fully empty bladder). * Had invasive urinary bladder procedures (ie, cystoscopy) within 7 days prior to screening. * Had phytotherapy within 2 weeks of screening and may need phytotherapy during the study. * History of low blood pressure (orthostatic hypotension, hypotension \[supine blood pressure less than 90/70 mm Hg\]), unstable angina, or a cardiovascular or cerebral vascular event (ie, transient ischemic attack \[TIA\], stroke) within the previous 3 months prior to enrollment, OR a history of dizziness, vertigo or any other typical signs and symptoms of low blood pressure. * Recent history (ie, within the past year) or active addiction, abuse, misuse of and/or dependence on drugs and/or alcohol. * Use of herbal therapies that may impact the study (eg, Saw Palmetto) within 2 weeks of screening and/or is predicted to need herbal therapies during the study. Individuals currently taking herbal therapies may be eligible for study if willing to complete a 2-week washout period. * Use of finasteride or a drug with a similar action during the 12 months prior to study screening. Individuals treated for short periods with 5-alpha reductase inhibitors (5ARIs) or drugs with antiandrogenic properties within 12 months of screening may be eligible for study. * Use of a non-approved (investigational) drug within the last 4 weeks prior to enrollment, or current participation in another clinical study. * Allergic or intolerant to finasteride and/or tamsulosin.