This chapter summarizes the results of the Trial of Mid Urethral Slings (TOMUS), in which women with stress urinary incontinence were randomized to a retropubic midurethral sling versus a transobturator sling. Bladder perforations and voiding dysfunction occurred only in the retropubic sling group; neurologic symptoms (weakness and numbness) were significantly more common in the transobturator group. Both objective and subjective measures of treatment success at 12 months were similar. Based on this and subsequent studies, retropubic and transobturator midurethral sling approaches appear to have similar outcomes at 12 months for the treatment of stress urinary incontinence. However, the approaches differ in their adverse-event profiles.