Personal experience with the treatment cryptogenic complex anal fistulas over the 10-year period from 1993 to 2002 is reported. Such fistulas accounted for 54 out of 255 fistulas observed (21.1%). Accurate anatomo-pathological classification, based on the connections between the fistulas and the sphincter and the musculature of the pelvic floor, is mandatory, as is thorough preoperative evaluation of ano-rectal function and of the risk of faecal incontinence. The surgical strategies used, in relation to the different kinds of complex fistulas treated, are schematically reported. A mixed technique consisting in fistulectomy-fistulotomy with setons was particularly preferred, because of the risk related to immediate dissection of the sphincter, especially when concurrent risk factors are present. As regards the results obtained, the surgical outcome consisted in healing in 49/54 cases (90.7%) as against recurrence or persistence of the fistula in 5/54 (9.3%). Minor complications occurred in 6/54 (11.1%); no major complications were observed and no cases of permanent faecal incontinence were reported. In conclusion, the surgical choice in cases of complex fistulas must lead to definitive, radical treatment of the lesion, at the same time avoiding irreversible anal incontinence due to severe lesions to the sphincter.