Photodynamic Therapy, also known as PDT, has emerged as a promising antimicrobial therapy. Enterococcus faecalis has been the most prevalent species in cases of endodontic failure. Safe and effective photosensitisers have been studied by many researchers for the photoinactivation of microorganisms. Tannins, from the French tannin, are phenolic compounds, natural colouring agents that are among the major active constituents derived from plants, justifying the traditional use of plants as anti-inflammatory and healing agents. We therefore tested tannin as a photosensitiser associated with photodynamic therapy as an adjunct to endodontic therapy.