The endodontic-periodontic lesion develops by extension of eitherp eriodontal destruction apically combining with an existingp eriapical lesion, or an endodontic lesion marginally, combining with an existing periodontal lesion.Most authors agree that both forms of therapy are essential fors uccessful healing of combined lesions. However, the problem arises over which lesion came first and what caused or perpetuated the clinical problem?In general, assuming that endodontic therapy is adequate, what is of endodontic origin will heal. However, in cases of combined disease, theprognosis rests with the severity and extent of the periodontal lesion and the efficacy of periodontal therapy.In conclusion, it is essential to understand that in endo-perio lesions, though the endodontic treatment is the more predictable of the two, however the success of treatment is dependent on the completion of periodontal therapy. The complete treatment of both aspects of endo-perio lesions is essential for successful long-term results.