An anal fissure is a superficial tear in the skin distal to the dentate line and is a cause of frequent emergency department visits. In most cases, anal fissures are a result of hard stools or constipation, or injury. Anal fissures are common in both adults and children, and those with a history of constipation tend to have more frequent episodes of this condition. Anal fissures can be acute (lasting less than six weeks) or chronic (more than six weeks). The majority of anal fissures are considered primary and typically occur at the posterior midline. A small percentage of these may occur at the anterior midline. Other locations (atypical/secondary fissures) can be caused by other underlying conditions that require further workup. The diagnosis of an anal fissure is primarily clinical. Several treatment options exist, including medical management and surgical options.Causes of anal fissures commonly include constipation, chronic diarrhea, sexually transmitted diseases, tuberculosis, inflammatory bowel disease, HIV, anal cancer, childbearing, prior anal surgery, and anal sexual intercourse. The majority of acute anal fissures is thought to be due to the passage of hard stools, sexually transmitted infection (STI), or anal injury due to penetration. A chronic anal fissure typically is a recurrence of an acute anal fissure. It is thought to be also caused by the passage of hard stools against an elevated anal sphincter tone pressure, with symptoms lasting greater than six weeks. Underlying conditions such as inflammatory bowel disease, tuberculosis, HIV, anal cancer, and prior anal surgery are predisposing factors to both acute and chronic atypical anal fissures. Approximately 40% of patients who present with acute anal fissures progress to chronic anal fissures.