Endoanal ultrasound (EAUS) and endorectal ultrasound (ERUS) have been introduced to clinical use since the 1980s. The techniques have been used to assess various anorectal disorders and conditions, including anorectal abscess and fistula, fecal incontinence, anorectal tumor, anorectal pain and occasionally evaluation of adjacent pelvic pathology. Information acquired includes anatomical location of disease, extent of disease, involvement of anal sphincter by disease and the status of anal sphincter. This information is valuable for treatment planning, prevention of disease recurrence, prevention and/or correction of sphincter defect and follow-up evaluation. The technique is cheap, simple, well tolerated, and repeatable with acceptable accuracy. Although the interpretation is operator-dependent, technology has developed to improved image quality such as 3D-reconstruction, peroxide-enhanced technique and volume render mode. This chapter reviews the current application of anorectal ultrasound in the common anorectal disorders.