The anal fissure, a lesion frequently encountered during proctological practice, is characterized by a painful symptomatology which greatly exceeds it anatomic entity. At times it reaches such proportions that it is more painful than anything the patient has ever felt before. It is an acute, solitary, superficial ulcer, in 75% of the cases located on the posterior midline of the distal anal canal, which is cutaneously lined. It has considerable difficulty in healing spontaneously and represents one of the most frequent causes of anal pain and bleeding. Frequently it is considered as hemorrhoids, not only by the patient himself, but by the physician as well.