OBJECTIVE: To compare two new generation antimuscarinics at their recommended doses for treatment of overactive bladder syndrome (OAB). METHODS: A prospective, double blind, double-dummy, two-arm, parallel-group, 12-week study was conducted to compare the efficacy and safety of solifenacin 5 or 10 mg and tolterodine extended release (ER) 4 mg once daily in OAB patients. After 4 weeks of treatment patients had the option to request a dose increase but were dummied throughout as approved product labelling only allowed an increase for those on solifenacin. RESULTS: Solifenacin, with a flexible dosing regimen, showed greater efficacy to tolterodine in decreasing urgency episodes, incontinence, urge incontinence and pad usage and increasing the volume voided per micturition. More solifenacin treated patients became continent and reported improvements in perception of bladder condition assessments. The majority of side effects were mild to moderate in nature, and discontinuations were comparable and low in both groups. CONCLUSIONS: Solifenacin, with a flexible dosing regimen, was found to be superior to tolterodine ER with respect to the majority of the efficacy variables.