Endodontic–periodontal lesions present challenges to the clinician as far as diagnosis and prognosis of the involved teeth are concerned. Treatment and prognosis of endodontic–periodontal diseases vary and depend on the cause and the correct diagnosis of each specific condition. The success of management of a combined periodontal and endodontic lesion depends on the elimination of both of the disease processes. Systematic examination combined with relevant investigations always provide a correct direction toward optimum treatment plan. This article presents the clinical effectiveness of platelet rich fibrin (PRF) in the treatment of a deep intra bony defect associated with an endo–perio lesion.