A new classification of female stress urinary incontinence was made according to the results of transrectal ultrasonography of the urinary bladder and urethra (cystourethrography) studied in 67 women with genuine stress urinary incontinence (SUI). This classification is based on the following changes of the bladder and urethra on abdominal straining: hypermobility of the urethra, bladder neck incompetence, urethral sphincter incompetence and presence of a cystocele. Five types of SUI has been classified. We believe that this new classification can provide a better understanding of the anatomical changes as well as the pathophysiology of SUI. In addition, it can serve as a guideline of proper surgical management for SUI.