Based on the experience of more than 6 500 patients with perianal suppurations, the authors conclude that the term of ano-rectal fistula should be rejected. The fistulas are rectal (secondary to an organic infection rectocolonic, or iatrogenic) or anal (with a cryptic starting point). The rectal fistulas are always complex for their internal opening being located in the rectal ampulla, they take the sphincteric apparatus as a whole and involve a major risk of post operative incontinence. Some of the anal fistulas are spontaneously complicated. It is the case of fistulas the track of which is located high in the sphincter, of those having multiple extensions, of some horse shoe fistulas with which the communication between the two ischio-rectal spaces is made by unusual passages. Most of them are iatrogenic. Without a doubt the complexity of some fistulas has been favoured by the prolonged and repeated use of antibiotics, but more often they are due to technical faults such as creation of false track during the search of the internal opening towards the superior pelvi-rectal space of towards the rectal ampulla with perforation situated more or less high up. The solution always difficult of therapeutics problems set by such cases should be looked for in the space of time placed between the operations, that alone allows to bring back progressively the complex tracks to their simple tracks.