Solifenacin Succinate Versus Tolterodine 4mg Once Daily

Inclusion Criteria: At study entry: * Patient is willing and able to complete the micturition diary correctly * Symptoms of overactive bladder (including urinary frequency, urgency or urge incontinence) for \>= 3 months At randomization: * Patient must experience frequency of micturition on average \>= 8 times per 24 hour period during the 3 day micturition diary period * Patient must experience at least one of the following symptoms during the 3 day micturition diary period: * At least 3 episodes of urinary incontinence or, * Patients must exhibit urgency at least 3 times Exclusion Criteria: At study entry: * Pregnant women or women who intend to become pregnant during the study or women of childbearing potential who are sexually active and practising an unreliable method of birth control or will be lactating during the study. Reliable contraceptive methods are intra-uterine devices, contraceptive pills of combination type, hormonal implants and injectable contraceptives * Clinically significant outflow obstruction (at the discretion of the investigator) * Significant post void residual volume (PVR\>200ml) * Significant stress incontinence or mixed stress/urge incontinence where stress is the predominant factor as determined by the investigator * Patient with a neurological cause for abnormal detrusor activity * 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 * Uncontrolled narrow angle glaucoma, urinary or gastric retention or any other medical condition which in the opinion of the investigator makes the use of anticholinergics contra-indicated * Non drug treatment including electrostimulation therapy or start of a bladder training program during the 2 weeks prior to entry into, or during the study * Use of drugs intended to treat urinary incontinence * Diabetic neuropathy * Known or suspected hypersensitivity to solifenacin, tolterodine, other anticholinergics or lactose * Any clinically significant condition, which in the opinion of the investigator makes the patient unsuitable for the trial * Participation in any clinical trial within 30 (90 in the UK) days prior to randomisation * Employees of the Yamanouchi Group, third parties associated with the study, or the study site At randomization: * Patient who did not complete the micturition diary according to the instructions * Total daily urine volume \> 3000 ml as verified in the micturition diary