Inclusion Criteria:

• Subject is willing and able to complete the micturition diary and questionnaires correctly
• Subject has symptoms of overactive bladder for ≥ 3 months
• Subject experiences frequency of micturition on average ≥ 8 times per 24-hour period during the 3-day micturition diary period
• Subject must experience at least 3 episodes of urgency (grade 3 or 4) with or without incontinence, during the 3-day micturition diary period

Exclusion Criteria:

• Subject is breastfeeding, pregnant, intends to become pregnant during the study, or of childbearing potential, sexually active and not practicing a highly reliable method of birth control
• Subject has significant stress incontinence or mixed stress/urge incontinence where stress is the predominant factor
• Subject has an indwelling catheter or practices intermittent self-catheterization
• Subject has diabetic neuropathy
• Subject has evidence of a symptomatic urinary tract infection, chronic inflammation such as interstitial cystitis, bladder stones, previous pelvic radiation therapy or previous or current malignant disease of the pelvic organs
• Subject receives non-drug treatment including electro-stimulation therapy
• Subject has severe hypertension
• Subject has a known or suspected hypersensitivity to tolterodine, other anticholinergics, YM178, other ß-AR agonists, or lactose or any of the other inactive ingredients
• Subject has been treated with any investigational drug or device within 30 days (90 days in the UK for all clinical studies except 178-CL-046)
• Subject had an average total daily urine volume > 3000 mL as recorded in the 3-day micturition diary period
• Subject has serum creatinine >150 umol/L, AST and/or ALT > 2x upper limit of normal range (ULN), or γ-GT > 3x ULN
• Subject has a clinically significant abnormal ECG