This chapter reviews the diagnostic criteria, pathophysiology and differential diagnoses of functional anorectal disorders (faecal incontinence, functional anorectal pain and functional defecation disorders). Practical recommendations relating to management and treatment of functional anorectal disorders are provided. The diagnosis of functional defecation disorders (FDDs) is based on symptoms and physiological testing. In the Rome IV criteria patients are required to fulfil diagnostic criteria of functional constipation and/or Irritable Bowel Syndrome (IBS) with constipation. Faecal incontinence (FI) can range from faecal seepage to complete loss of bowel control. While the staining of underwear is part of the current classification, flatus is not part of the Rome IV criteria. The prevalence of functional anorectal pain has been estimated to be 8"–18", with both sexes affected equally across almost all age groups in the community. FDDs are part of the spectrum of chronic constipation with outlet obstruction, characterized by paradoxical contraction, insufficient relaxation of pelvic floor muscles or inadequate propulsive forces.