This is a prospective, randomized, double-blind study comparing intravesical injection of BOTOX to placebo. Study subjects will be randomized (1:1 ratio) to one of the following treatment groups:

Group 1 n=20 BOTOX® 200U Group 2 n=20 Placebo BOTOX® (saline) At Visit 2 (Treatment, Day 0), subjects will receive one injection cycle of BOTOX (200U) or placebo (saline). The study duration is approximately 284 days and consists of a Screening Visit (Day -7 to -14), a Treatment/Randomization Visit (Visit 2, Day 0), and Follow-up Visits at 7, 30, 90, 180, and 270 Days. Telephone Follow-ups will be made 3 days following the injection cycle.

Subjects demonstrating an insufficient response to treatment may receive an open-label injection cycle of BOTOX (200U) at Day 90. Subjects receiving this injection will re-commence Follow-up Visits and be followed for an additional 270 days.

Inclusion Criteria:

1. Male outpatients of any race, between 40 and 90 years of age.
2. Clinical signs and symptoms of frequency (>=8 micturitions/day) and urgency (>=2 episodes/day).
3. Urodynamic history consistent with OAB that developed in conjunction with BPO and that persists for at least 3 months post TURP or PVP, RRP or other obstruction relieving procedure.
4. OAB inadequately controlled with anticholinergic medications, as per Investigator opinion.
5. Qmax >12mL/s with a voided volume of >125mL.
6. IPSS >12, with IPSS QoL >3 at study Visit 1.
7. Willing to use clean intermittent catheterization (CIC) to empty the bladder or is willing to have an indwelling catheter, if necessary following study treatment.
8. Able to understand the requirements of the study, including completing questionnaires and signing Informed Consent/HIPAA.

Exclusion Criteria:

1. Known history of interstitial cystitis, uninvestigated hematuria, bladder outlet obstruction due to vesical neck contracture, mullerian duct cysts, urethral obstruction due to stricture/valves/sclerosis of urethral tumor, radiation cystitis, genitourinary tuberculosis, bladder calculi, or detrusor-sphincter dyssynergia.
2. Known history of clinically significant cardiovascular disease, cerebrovascular disease, or arrhythmia.
3. History of spinal cord injury or multiple sclerosis, or other neurological disease which may be contributing to OAB.
4. Known history of hydronephrosis.
5. Current indwelling catheter, or removal of chronic catheter <1 month prior to study entry.
6. Non-compliance with wash-out periods for prohibited medications/therapies (Supplement I).
7. Evidence of Urinary Tract Infection according to local standard of care.
8. Serum PSA of >10ng/mL.
9. 24 hour total volume voided >3000 mL of urine. [As determined by completion of a patient bladder diary during the screening period]
10. Medical condition that may increase their risk of exposure to botulinum toxin including diagnosed Myasthenia Gravis, Eaton-Lambert Syndrome, Amyotrophic Lateral Sclerosis or any other disease that might interfere with neuromuscular function.
11. Allergy or sensitivity to any component of BOTOX® (Section 5.2).
12. Known uncontrolled systemic disease.
13. Evidence of recent alcohol/drug abuse.
14. Subjects who, in the opinion of the Investigator, have a significant condition that puts them at significant risk, may confound study results, or interfere with study participation.
15. History of poor cooperation, non-compliance with medical treatment, or unreliability.

Adverse Events were collected over 1 year