Tolterodine is a potent and pure muscarinic receptor antagonist that was developed specifically for the treatment of overactive bladder. Recently, studies revealed that tolterodine was effective, safe and well tolerated in adults with OAB and urodynamically confirmed BPO.However, the optimal dosage of antimuscarinic for the treatment of OAB coexisting BPO was not yet fully assessed. In real clinical situation, some patients complain voiding difficulty after addition of antimuscarinics and want to stop antimuscarinics.It is probable that a lower dosage of antimuscarinics combined with alpha-adrenergic antagonists can be used safely in OAB patients with BOO, with the same efficacy.