Anal adenocarcinoma revealed by a fistula-in-ano occurs rarely. Authors report a case in a 56 year-old man. The pathogeny is still unknown. Symptomatology has no specificity and the diagnosis is often late, in an advanced stage of the sickness. Recurrent or non recurrent fistula-in-ano requires multiple biopsies for pathology analysis in order to screen a related cancer. Tumor dimension, lymph node involvement, histologic grade and treatment modality are independent prognosis factors for survival. Our objective is to show physiopathological, clinical and therapeutical characteristics from a review of the literature.