We summarize the prevalence and causes of constipation and incontinence in an elderly, drawing particular attention to the roles of immobility, dietary fiber, and dehydration. The physiology of fecal impaction is described in detail, and neurological and mechanical causes (rectal prolapse, rectocele, and hemorrhoids) of constipation are discussed. Consideration is also given to constipation associated with diverticular disease and ulcerative colitis. We also discuss the pathogenesis of fecal incontinence in the elderly, paying particular attention to fecal impaction and neurological causes that result in both constipation and incontinence. The importance of previous obstetric trauma and pudendal enuropathy is emphasized. We conclude with detailed guidelines of the clinical assessment and management of an elderly patient with a disorder of defecation.