Aim: comparison between surgical and chemical sphincterotomy for treatment of chronic anal fissure. 
Methods: 160 patients were equally randomly divided into 4 groups treated by: lateral internal sphincterotomy (Group 
І), local Diltiazem ointment (Group ІІ), local Glyceryl trinitrate ointment (Group ІІІ), or injection of Botulinum toxin 
into the internal anal sphincter (Group ІV). Anal manometry was measured before and 3 months after treatment. 
Patients were followed up for 5 years. 
Results: Mean time for complete pain relief was 5.68±7.77 days (Group I), 15.7 ± 5.87 days (Group II), 15.6 ± 5.90 days 
(Group III) and 2.67 ± 3.60 days (Group IV). Mean healing time was 4.48±1.20 weeks (Group I), 5.12±1.13 weeks (Group 
II), 5.00±1.12 weeks (Group III) and 5.06±1.31 weeks (Group IV). Mean resting and squeeze anal pressures decreased 
significantly after sphincterotomy. Recurrence rate was 10% in Group I, 65% in Group II, 57.5% in Group III and 52.5% 
in Group IV. 
Conclusion: Lateral internal sphincterotomy is easy and satisfactory, with minimal complications and recurrence. 
Medical sphincterotomy is safe, and easy, with mild complications. Its effect is reversible. Relapse after it is common. It 
is worth trial before surgery or in patients that cannot or unwilling to undergo surgery.