A Study Comparing the Efficacy of an Alpha Blocker Versus an Alpha Blocker Plus Solifenacin in Men With Overactive Bladder

Inclusion Criteria: * Persistent symptoms of OAB as verified by the 3 day voiding diary, defined by: * symptoms of urinary urgency (defined as a level of \>=3 in a 5 point urgency scale) at least two episode per 24 hours and * symptoms of urinary frequency ( \>8 micturitions per 24 hours) * On a stable dose of tamsulosin for at least 1 month Exclusion Criteria: * Previous history of acute urinary retention * Patients have a baseline post-void residual (PVR) which exceeded 50% of voided urine volume * Any condition that is a contraindication for anticholinergic treatment, including uncontrolled narrow-angled glaucoma, urinary retention or gastric retention * Symptomatic acute urinary tract infection (UTI) during the screening period * Treatment within the 14 days preceding randomization, or expected to initiate treatment during the study with any anticholinergic drugs and drug treatment for overactive bladder * A 5-alpha reductase inhibitor if started less than 3 months prior to screening * Patients with previous urethral, prostate or bladder neck surgery