Objective:To evaluate the effectiveness and applied value of multislice spiral computed tomography (MSCT) plain and enhanced scan combined with fistulography to the locational diagnosis of anal fistula. Methods:Preoperatively MSCT examination was performed in 32 patients with clinically suspected anal fistulas between July 2004 and May 2006 and results were compared with microsurgical and followup findings.Multiplanar reconstruction (MPR) and volume rendering (VR) were adopted to reconstruct 3D images in all cases.Images of MSCT were reviewed by professional radiologist. Results:On MSCT examination,4 patients had no fistula.Five patients had simple fistulas.Twenty-three patients had complex fistulas.All patients were confirmed by operation.At the same time 8 cases were misdiagnosed in surgery’s professional examination.Six patients had lowlocated fistulas.Twentytwo patients had highlocated fistulas.All patients were confirmed by operation,but on surgery’s professional examination 8 cases with highlocated fistulas were misdiagnosed as lowlocated fistulas.Three cases of extrasphincteric fistulas were misdiagnosed as suprasphincteric fistulas.For detection of the presence of internal openings,secondary tracts,abscesses,MSCT had a accuracy of 62.1％,89.3％,100.0%.The 3D shape and track of fistula could be well demonstrated by VR，while MPR including curved planar reconstruction (CPR) could well show the site of anal fistula and its relationship with the sphincter complex and the levator ani muscle. Conclusion:MSCT combined with fistulography is a very effective and reliable method for the locational diagnosis of anal fistula.