Anal fissure. Anal fissure is a painful proctological disease that most often affects young patients equally in both sexes. It significantly worsens the quality of life and requires rapid care. The anal fissure is most often located in the posterior anal commissure and frequently surmounted by a skin tag which can hide it and wrongly carry the diagnosis of hemorrhoids. Differential diagnoses such as carcinoma, Crohn's disease, sexually transmitted infection, etc. should be mentioned in case of atypical presentation. Its pathophysiology remains controversial, but in most cases, it results from the trauma of the passage of hard stools on an hypertonic anus. Medical treatment can cure just over half of patients. Surgery is reserved for failures of medical treatment and hyperalgesic fissure. In France, fissurectomy is the most commonly performed procedure while on the other side of the Channel or the Atlantic, lateral internal sphincterotomy is considered as the reference technique.