Fistulography classifies anal fistulas in low-below puborectalis muscle-, high-above puborectalis muscle-, and middle. This classification increases the scope and accuracy of radical surgery. In order to improve the diagnostic reliability of anal fistulography the authors point out the importance of radio-opaque markers for anatomical definition of the anorectal region. Thirty patients (25 males and 5 females; mean age: 47 years) were studied by anal fistulography using radiopaque markers: a Foley's 22 Fr catheter, with distal balloon filled of idrosoluble radiopaque contrast medium, was placed in the anal canal; a metal marker was fixed to the anus. In order to demonstrate the relationship between fistula and puborectalis muscle, we subdivided the anal canal in 3 equal segments: high, middle and low. The idrosoluble contrast medium for fistulography is injected through a pediatric Foley's catheter 8 Fr when external opening is large enough, and through a K7072 endovenous catheter when the opening is small. Fistulous tract was visible in all patients: internal fistulous opening in 23/90 cases, and relationship of fistulous tract to puborectalis muscle in 25/30 (83.3%). In demonstrating either secondary fistulous tracts or abscesses, fistulography with radiopaque markers was correct in 60% of cases; in 20% of patients some of the above-mentioned complications were demonstrated, and in the 20% no complications at all were detected.