Background: Chronic anal fissure is one of the most common annoying anal disorders. Many medical treatments are used to help the healing of the fissure but the recurrence rate is so high after the stoppage of medicine, so the surgical treatment by lateral internal sphincterotomy is still the best way of management. Objective: In our study, we compared two different techniques of lateral sphincterotomy either open or closed techniques. Patients and methods: This is a prospective study done on 150 patients with chronic anal fissures managed by lateral sphincterotomy between June 2017 till May 2019. The patients were divided into two groups (group A) 70 patients managed by open internal sphincterotomy and (group B) 80 patients managed by closed lateral sphincterotomy. Results: In the present study, the main complaint of most patients was anal pain during defecation. The most common site of the fissure was posterior at midline with Sentinel pile. Delayed postoperative healing was found in 4.28% of group A. The mean pain score and duration of hospital stay were lower in group < strong> B. The risk of post-operative complications such as anal fistula and bleeding was high in group A than in group B. Conclusion: Closed lateral internal sphincterotomy is a better choice for the management of chronic anal fissure as it was less in postoperative complications and early recovery.