Patients with presumed non-obstructive BPH (Q (max )>or= 15 ml/s) treated with tolterodine ER 4 mg/day for OAB symptoms, alone or added to unsuccessful alpha-blocker treatment of >or=6 weeks duration, were observed for 12 weeks in a non-interventional study to generate real-life efficacy and safety data. Patients completed the IPSS, the OAB-q and a 2-day micturition diary at baseline and 12 weeks. PVR was determined sonographically. Seven hundred and forty one patients were analysed. Mean PVR did not increase (25.4 +/- 26.5 vs. 29.3 +/- 30.9 ml at baseline). AUR requiring catheterization occurred in two patients, acute UTI in four patients. Median IPSS total scores decreased from 17 to 10, IPSS QoL scores from 4 to 2, OAB-q symptom bother scores from 50.0 to 22.5 and OAB-q HRQL scores increased from 59.2 to 81.6. In men with OAB symptoms and presumed non-obstructive BPH, tolterodine ER provided considerable symptomatic and QoL improvements with a low risk of AUR, acute UTI, or increased PVR.