Many methods of evaluating anatomic deformity of the urethrovesical angle are available. A new diagnostic device has been developed to determine the degree of rotation of the urethral axis, thus differentiating between type I and type II deformities causing stress incontinence. Preliminary study in 62 patients indicates that the instrument is accurate, simple, and easily interpreted. The device also has the advantage of being easily constructed, disposable, and inexpensive.