Anal fissure is a very common acute condition that is presented in majority of the world population. To evaluate the outcome of partial lateral internal sphincterotomy technique for chronic anal fissure. 100 Patients of chronic anal fissure attending general surgery OPD and admitted to General Surgery department of Vivekananda Institute of Medical Sciences, Kolkata, West Bengal, India, West Bengal for sphincterotomy technique. It was found that post–operative fissure healing rate was 99% at 6 weeks and the complete fissure healing rate was found at 10 weeks. Fissure healing rate was statistically significant. Our study showed that post–operative no bleeding was 76% at 72 hours, 94% at weeks, 98% at 6 weeks and 99% at 10 weeks. So bleeding was deceased during follow–up period which was statistically significant. Postoperative one patient was anal incontinence fecal soiling and flatus, three patients were surgical site infection and all patients were no recurrence during follow–up period