The purpose of this study is to evaluate the efficacy and safety of tolterodine in impacting the primary symptom or complaint of patients with OAB.

Inclusion Criteria:

• self-reported symptoms of OAB for ≥ 3 months prior to screening
• OAB as defined by urinary frequency (a minimum of 8 micturitions per 24 hours)
• urgency (defined as a strong and sudden desire to urinate) or urge incontinence a minimum of 2 episodes in 3 days, as confirmed by the micturition diary between screening and baseline
• patients who describe the degree of bothersomeness of their most bothersome OAB symptom as "moderately ", "a great deal ", or "a very great deal" per the OAB Bother Rating Scale

Exclusion Criteria:

• any condition that would contraindicate their usage of tolterodine once daily, including: narrow angle glaucoma, urinary retention, gastric retention
• any clinically significant local urinary tract pathology which could mimic the symptoms of OAB, such as infection or hematuria
• stress incontinence, functional, or overflow incontinence as determined by the investigator
• symptomatic acute urinary tract infection (UTI) during the run-in period, or recurrent UTIs defined by treatment for symptomatic UTI >3 times in the 12 months prior to participation in this clinical trial
• clinically significant urinary tract obstruction
• history of lower urinary tract surgery (e.g. prostate removal or destruction, incontinence surgery) within the past 3 months
• clinically significant interstitial cystitis or significant bladder pain syndrome