Longitudinal fissure in the anal mucous membrane, caused among other things by chronic hardness of the faeces or by haemorrhoids. Symptoms occur above all during defecation: severe, convulsive pain and loss of blood. The pain can persist for some time. The lost blood is not mixed with the faeces, is bright red, and the loss can be considerable. If the patient was not already prone to hardness of the faeces the condition can cause it, because fear of pain leads to unduly long retention. After diagnosis by careful examination of the anus, treatment can consist in the first place of softening the faeces by a varied diet or laxatives, thus putting the fissure under less pressure, so that it can heal. The fissure can be relieved if the anus is stretched, or a painkiller injected. If this is not successful, the fissure can be removed by surgery.