The U.S. elderly population (≥85 years old) is estimated to increase from 5 to 20 million people between the years 2000 to 2050. Among the medical disorders facing the elderly, anorectal problems are not only highly prevalent, but cause significant morbidity and mortality, and have deleterious effects on health care burden and quality of life. These include disorders such as fecal incontinence, fecal impaction with overflow fecal incontinence, chronic constipation, dyssynergic defecation, hemorrhoids, anal fissure, and pelvic floor disorders. Here, we discuss the latest advances in age-related changes in anal sphincter morphology and function, changes in cellular and molecular biology, alterations in neurotransmitters and reflexes, and their impact on functional changes of the anorectum in the elderly. These biophysiologic changes have implications for the pathophysiology of anorectal disorders. A clear understanding and working knowledge of the functional anatomy and pathophysiology will enable appropriate diagnosis and treatment of these disorders.