Being the final pathway for chyme and digestive residues, the colorectum influences bowel function critically. The most important and relevant symptoms of colonic dysfunction are diarrhea, constipation, urgency, and pain. Despite the effects of many investigators, over several decades, the motor physiology of the human colon is still relatively obscure. Most is known about patterns of colonic transit. In practice, measurements of transit are the best characterized and most widely available tests of colonic motor function. Colonic hypersensitivity, implying an abnormality of afferent signaling, is assuming greater importance in the pathophysiology of conditions as common as IBS and inflammatory bowel disease.