Objective To investigate the safety and feasibility of minimally invasive stealth lateral release operation in the treatment of chronic anal fissure . Methods Clinical data of 42 patients with chronic anal fissure who underwent minimally invasive stealth lateral release from May 2012 to May 2014 was analyzed retrospectively .We use the homemade fine steel wire to pierce into the sphincter ditch with a distance from the anus of 1 cm, and put the steel wire out above the dentate line .Then the wire was took out from the other edge under the skin through the needle of bobbin .After the needle was fixed by an assistant , the free end of the steel wire was pulled quickly to cut the internal sphincter tissue instantly . Results All the 42 patients were successfully treated and discharged without complications .The recovery time was in 7 -14 d, with an average of 9 d.The healing standards included disappeared symptoms and totally healed wound .All the patients were followed up for 3-6 months, with an average of 4 months.No recurrence was found . Conclusion Minimally invasive stealth lateral release in the treatment of chronic anal fissure is safe and feasible, with many advantages such as simple performance , reliable curative effect, fast recovery time, and less postoperative complications .