Fissure in ano is a common painful condition that can be found in children and adults alike. These wounds usually heal spontaneously in children but may require operative correction in adults. It is usually caused by constipation or a large traumatic bowel movement, and it is almost always located posterior. The fissure, which runs between the dentate line and anal verge, if deep enough exposes the internal sphincter muscle. This causes considerable spasm and pain. Chronic fissures may be associated with a hypertrophied anal papilla and a skin tag. Over a period of time, the internal sphincter muscle hypertrophies, becoming more effective in keeping the wound open, and preventing spontaneous closure of the fissure. Topical salves and fiber are usually effective early on. Once the wound becomes chronic, surgical repair is usually necessary.