A chronic anal fissure is a non-healing linear tear in the distal anal mucosa below the dentate line and is a painful entity. A fissure is defined as chronic when it fails to heal within 6 weeks from an acute attack1. This study is an attempt to compare efficacy of lateral internal sphincterotomy versus topical 2 % Diltiazem ointment for the treatment of chronic anal fissure. This prospective comparative study was done in our hospital during one and half year from February'11 to August'12. 50 patients were treated with 2 % Diltiazem ointment and rest 50 underwent lateral internal sphincterotomy for chronic anal fissure. Patients were followed for 8 weeks and thereafter evaluated for symptoms relief in both the groups. Observations were recorded at 2nd, 4th, 6th and 8th week regarding relief of symptoms like pain, bleeding per rectum, healing of ulcer and side effects of fecal incontinence in surgical group. All data were collected and analyzed accordingly. It revealed that 56 % were male and 44 % were female and maximum numbers of patients were in the age group 30-39 years. The chief complaints of patients at presentation—29 % had pain during defecation with constipation, 22 % bleeding per rectum and 49 % had only pain during defecation. Most of them (90 %) had posterior anal fissure. Most of the patients (63 %) had ulcer only. But in 37 % of cases there were ulcer with sentinel piles. Lateral internal sphincterotomy is the treatment of choice while treating chronic anal fissure, because of its simplicity, better healing rates, better patient satisfaction, minimal morbidity and low complication rates. Taking this option also helps the patient to resume his/her normal works earlier than that of topical 2 % Diltiazem ointment. KeywordsLateral internal sphincterotomy, 2 % Diltiazem ointment, chronic anal fissure.