A randomized, double-blind, placebo-controlled, four-way crossover, safety study of darifenacin versus oxybutynin was carried out on 76 patients with overactive bladder (OAB). Adults with OAB received 2 weeks each of darifenacin 15 and 30 mg once daily (q.d.), oxybutynin 5 mg three times daily (t.i.d.) and placebo, in random sequence at 10-day intervals. Darifenacin and oxybutynin significantly reduced incontinence episodes, and the number/severity of urgency episodes (all P<0.05 versus placebo). Improvements in OAB symptoms with darifenacin were dose-dependent. Dry mouth was less common with darifenacin 15 mg than oxybutynin (13% and 36%; P<0.05), while constipation was comparable (10% and 8%, respectively). Corresponding rates for darifenacin 30 mg were 34% and 21%, respectively. Patients only reported blurred vision or dizziness with oxybutynin (3% and 2%, respectively). Darifenacin (15 mg q.d.) provides comparable efficacy with improved tolerability versus oxybutynin (5 mg t.i.d.) in the treatment of patients with OAB.