To evaluate the efficacy of 5 and10mg solifenacin succinate in patients with urgency who have OAB syndrome (urgency, with or without urge incontinence, usually with frequency and nocturia) and wish to switch from tolterodine tartrate extended release to solifenacin succinate due to lack of sufficient improvement in urgency episodes

Inclusion Criteria:

• Patients with OAB who have been treated with tolterodine tartrate extended release for at least 4 weeks immediately preceding entry into the study, and wish to switch to solifenacin succinate due to lack of sufficient improvement in urgency episodes.
• Previous non-drug treatment of OAB is allowed if it has been established at least 4 weeks prior to Screening and is continued throughout the study.
• At least 3 urinary urgency episodes/24 hours while receiving tolterodine tartrate extended release documented in a 3-day patient diary in the pre-washout assessments on tolterodine tartrate extended release with or without urge incontinence described as OAB syndrome.
• Prior to treatment with tolterodine tartrate extended release, patients must have had OAB syndrome for 3 or more months.

Exclusion Criteria:

• Previous treatment with darifenacin
• Treatment with tolterodine tartrate extended release for less than 4 weeks prior to enrollment in the study.
• Significant stress incontinence or mixed stress/urge incontinence where stress is the predominant factor as determined by the investigator.
• Evidence of a urinary tract infection; chronic inflammation such as interstitial cystitis and bladder stones.
• Clinically significant outflow obstruction as determined by the Investigator
• Uncontrolled narrow angle glaucoma, urinary or gastric retention.
• All patients with severe renal or hepatic impairment will be excluded
• Patients with chronic severe constipation or history of diagnosed gastrointestinal obstructive disease.