This randomized multi-centre trial will recruit women with stress urinary incontinence who need surgical treatment for their condition. 300 women will be allocated either to receive a TVT Secur or a standard TVT surgical procedure. The main outcome is effectiveness of the procedure, determined using a 1-hour pad test (which tests for urine leakage) 12 months after surgery. The study will be carried out in 4 to 6 centers and will involve urogynaecologists, urologists and general obstetrician-gynaecologists: all clinicians will have received adequate training.