Objective To compare the efficacy and safety of the 30 mg extended release (ER) formulation of propiverine hydrochloride with the 4 mg ER formulation of tolterodine tartrate in patients with overactive bladder (OAB) in a non-inferiority trial. Patients and Methods Eligible patients, aged 18-75 years and with symptoms of OAB, were enrolled in this multicentre, randomized, double-blind, parallel-group, active-controlled study. After a 2-week screening period, patients were randomized at a 1: 1 ratio to receive either propiverine ER 30 mg or tolterodine ER 4 mg daily during the 8-week treatment period. Efficacy was assessed using a 3-day voiding diary and patient's self-reported assessment of treatment effect. Safety assessment included recording of adverse events, laboratory test results, measurement of post-void residual urine and electrocardiograms. Results A total of 324 patients (244 female and 80 male) were included in the study. Both active treatments improved the variables included in the voiding diary and in the patient's self-reported assessment. The change from baseline in the number of voidings per 24 h was significantly greater in the propiverine ER 30 mg group compared with the tolterodine ER 4 mg group after 8 weeks of treatment (full analysis set [FAS] -4.6 +/- 4.1 vs -3.8 +/- 5.1; P = 0.005). Significant improvements were also observed for the change of urgency incontinence episodes after 2 weeks (P = 0.026) and 8 weeks (P = 0.028) of treatment when comparing propiverine ER 30 mg with tolterodine ER 4 mg. Both treatments were well tolerated, with a similar frequency of adverse drug reactions in both the propiverine ER 30 mg and tolterodine ER 4 mg groups (FAS 40.7 vs 39.5%; P = 0.8). More patients treated with tolterodine ER 4 mg discontinued the treatment because of adverse drug reactions compared with propiverine ER 30 mg (7.4 vs 3.1%). Conclusions Propiverine ER 30 mg was confirmed to be an effective and well-tolerated treatment option for patients with OAB symptoms. This first head-to-head study showed non-inferiority of propiverine ER 30 mg compared with tolterodine ER 4 mg.