Ultrasound imaging has significantly enhanced our ability to visualize the anatomy and understand the functionality of the female pelvic floor. This chapter will focus on the application of 2D/3D transperineal and 2D/3D endovaginal ultrasound imaging in evaluating the posterior compartment. We will briefly review the normal anatomy, ultrasound techniques, and equipment. The chapter will include a detailed discussion of specific disorders of the posterior compartment, such as rectocele, enterocele, intussusception, rectal prolapse, and pelvic floor dyssynergy. Additionally, we will explore certain 3D endovaginal ultrasound findings that may elucidate the presence of obstructed defecation symptoms in patients who do not exhibit obvious abnormalities upon physical examination. Furthermore, the role of 3D endovaginal imaging in identifying and characterizing mesh in the posterior compartment will also be addressed.