Purpose: this prospective study was undertaken to compare lateral conventional (CLIS) versus tailored lateral 
sphincterotomy(TLIS) in treatment of chronic anal fissure as regards manometric studies, patient acceptance, healing, 
recurrence and continence disorders. 
Methods: In the period from July 2001 to March 2002, this study included 42 patients suffering from chronic anal fissure. They were randomized into Group (A) that included 22 patients who were subjected to (CLIS) and Group (B) that included 20 patients who were subjected to (TLIS). Preoperative anorectal manometric studies and endoanal ultrasound (EAUS) were done. Patients were followed up for a period of 3- 12 months. 
Results: Healing of anal fissures had occurred within 4-6 weeks in almost all patients. 15% in group B developed recurrence 
of the fissure within two months . 31.8% in group A, reported diminished ability to differentiate between flatus and liquid 
stool. This was transient in 18.2% but continued in 13.6%. In group B, 10% suffered transient soiling. Postoperative 
manometric evaluation revealed significant decrease in both maximum resting and maximum squeeze pressures and 
significant increase in the resting CV following both CLIS and TLIS. Also, Ultrasound evaluation have confirmed the 
competence of sphincterotomy in 39/42 patients (92.9%). 
Conclusion: incontinence is directly related to the extent of muscle division at internal sphincterotomy and that the success rate of TLIS closely approximates that of CLIS with preservation of more anal sphincter muscle and physiology.