The target of this work is to evaluate the translabial ultrasonography (US) reliability as valid alternative to chain cystography in the pre and post operative assessment of patients with stress urinary incontinence (SUI). From June 1996 to May 1999, we studied 448 patients ranging in age from 35 to 90 years old with SUI from defect of anatomic support. Patients underwent translabial ultrasonography. The translabial US was performed with the patient in lithotomic position using a linear 7.5 MHz probe. The bladder was slightly filled, and the probe positioned longitudinally at the introitus to evaluate downwards and posterior rotation of bladder neck and urethra in basal conditions as well as during the abdominal strain. The evaluation of the anterior urethral angle of the 448 patients who underwent translabial US showed that, during the abdominal strain, all the patients with SUI had a very significative rotation of the urethral axis compared to continent women. Translabial US is a quick, simple, reliable non-invasive procedure. It may be used routinely for the pre and post-operative evaluation of anti-incontinence surgery.