To explore the usefulness of intraluminal ultrasound (US) for diagnostic imaging of the female urethra, 22 female patients with different degrees of urinary incontinence and 10 female patients with normal continence underwent examination by means of a 20-MHz intravascular US system. Contiguous sections were used for three-dimensional reconstructions on a personal computer-based system in two patients. The circumference and area of the internal urethral sphincter were measured in all patients; the measurements were obtained by means of manual delineation of the inner and outer contours of the sphincter. A correlation was found between (a) area and circumference and (b) the degree of incontinence (P < .01). No patient with normal urinary continence showed a reduced sphincter size (a circumference smaller than 2.8 cm). Intraurethral US, which yields images of the urethra and surrounding tissues, may become an important adjunct to urethrography and functional methods (assessment of urodynamics) for the diagnostic evaluation of incontinence.