Urethral dilatation is a commonly undertaken intervention for a variety of urinary complaints including overactive bladder symptoms. There is however very little evidence for its efficacy, and no randomized trial evidence. The aim of this study is to ascertain the effect of urethral dilatation on overactive bladder symptoms and on voiding parameters. The null hypothesis is that there will be no difference in symptoms or voiding parameters between the urethral dilatation and sham groups.