Urethral bulking is a procedure that can be performed in an ambulatory setting for the treatment of stress urinary incontinence in the setting of lack of urethral mobility. Numerous types of urethral bulking agents (UBA) have been used since its first introduction as a collagen implant in the 1930s and the procedure has been evolving through the years. Ultrasound imaging has made it possible to visualize the implanted UBAs and the anatomic location of those agents. These agents are best imaged using specialty 3D endovaginal ultrasound transducers. Urethral bulking can be readily imaged with transducers commonly found in most ultrasound departments. However, during a pelvic or renal examination, a sonographer may inadvertently find an image with an echogenic structure near the urethrovesical junction in patients with a history of urethral bulking. Familiarizing oneself with the sonographic appearance of UBAs and optimizing techniques to obtain improved images of these agents may eliminate the need for additional imaging for the patient. In this chapter, we will focus on the sonographic characteristics of UBAs and on knowing when and how to use appropriate probes to image the urethra. We will also describe using 2D/3D perineal and 3D endovaginal ultrasound imaging to assess urethral bulking. Normal anatomy, ultrasound techniques, and equipment will be briefly reviewed. A detailed discussion of the specific and appropriate implanting location of the UBA is included. We will also discuss the use of 3D endovaginal imaging to identify and describe the location and distribution of UBAs following uncomplicated transurethral injection.