Gastrointestinal tract (GIT) is commonly affected by tuberculosis; however isolated tuberculous involvement of the rectum is rare. A tuberculosis origin must be considered when the cause of perianal and rectal lesion is unclear to avoid delay in the diagnosis and treatment. We report an uncommon case of primary isolated rectal tuberculosis. Case report : Patient 45 years old, with no pathological history, who has been presenting low abundance hematochezia associated with abdominal pain, The rectoscopy is indicated, which showed a rectal ulcer at 8 cm from the anal margin, with erythematous mucosa. Multiple biopsies were performed, with the result of histological examination in favor of rectal tuberculosis. The search for mycobacterium tuberculosis by PCR technique (genexpert test) was positive. The patient was started on Anti- Koch’s Treatment (AKT) for six months. He responded very well to this anti tuberculosis therapy and after six months of follow-up he was completely asymptomatic. Conclusion : Rectal tuberculosis is a rare location difficult to diagnosis, usually improve after administration of an anti-bacillary treatment.