PURPOSE: To demonstrate the anatomy of the female pelvic floor and to determine the anatomic differences between normal controls and women with stress urinary incontinence, using MRI. MATERIALS AND METHODS: Five healthy, young, nulliparous women and 12 with stress urinary incontinence un-derwent MR imaging. We obtained FSE T2-weighted axial images, 3mm thick, of the region extending from the urethrovesical junction to the perineal membrane. The following parameters were determined : angle, asymmetry and signal intensity of the levator ani muscles, the distance between the urethra and symphysis, and the presence, shape and angulation of urethropelvic ligament. RESULTS: In contrast to normal controls, frequent findings in women with stress incontinence were as follows : increased angle(43%), asymmetry(43 %) and higher signal intensity(67%) of the levator ani muscles; increased distance between the urethra and symphysis; loss(43 %), discontinuity (60 %) and dorsal angulation(43%) of the urethropelvic ligament. CONCLUSION: In women with stress urinary incontinence, MRI clearly demonstrates the anatomy of the female pelvic floor, changes in the levator ani muscles, the distance between the urethra and symphysis, and the ure-thropelvic ligament. The modality can therefore be used to evaluate the anatomical changes occurring in cases of stress urinary incontinence.