Intestinal involvement in Parkinson's disease (PD) has been known since James Parkinson's initial description of the disease in 1817. Relatively little attention has been directed toward small intestinal dysfunction in PD, but some evidence has accumulated that small intestinal motility may, indeed, be impaired in PD. However, the clinical consequences of any such dysfunction have not been clearly delineated. Much more information is available regarding colonic and anorectal dysfunction in PD. Diminished bowel movement frequency, presumably reflecting colonic dysmotility with consequent slowed colonic transit, is present in a significant percentage of individuals with PD, reported figures ranging from 20 to 77%. Anorectal dysfunction, characterized by both excessive straining and a sense of incomplete emptying, develops even more frequently in PD, affecting more than 60% of patients. Both central and enteric nervous system dysfunction may have a role in the generation of these intestinal and anorectal abnormalities. Recognition of two components of intestinal dysfunction in PD-slow-transit constipation and anorectal defecatory dysfunction-will hopefully open the therapeutic door to more specific and effective treatment for these troubling and occasionally disabling features of PD.