Purpose: The purpose of this study was to demonstrate loose silk seton actually acts as a slow cutting seton contrary to the idea of simply drainage. Besides, to show the effect of loose seton on patient's incontinence is mostly proportional to the degree of division of the sphincter muscle. Design: Fifty patients with high transsphincteric fistulas were treated with loose seton technique. We measured the length of high sphincteric fistula tracts, pre-and postoperative anal sphincter pressures and incontinence scores. Results: Loose seton with heavy silk resulted in 72% percent of progressive migration of the fistula tract caudally. The more the progressive migration of the loose seton loop, the less the pressure drop in both resting and squeezing in manometric studies. This study is limited by its retrospective design in prospectively collected data and covers relatively small number of patients. Conclusion: Seton is still useful technique in high perianal fistula surgery. Defining this technique as simply "loose" seton is misnomer since it acts as a slowly cutting seton and results in progressive migration of the fistula tract caudally. The more the progressive migration of the loose seton loop, the less the pressure drop would be possible after postoperatively.