Uterine fibroids (leiomyomas) are the most common benign tumors of the female reproductive tract. On ultrasound, they typically appear as hypoechoic, well-defined masses that distort the normal uterine contour or echotexture. They may contain calcifications (producing acoustic shadowing) and can be submucosal, intramural, or subserosal in location. Large fibroids may cause posterior acoustic shadowing that limits visualization of the uterine cavity and ovaries. Color Doppler shows peripheral and central vascularity. Fibroids are a common cause of abnormal uterine bleeding and pelvic pressure.