Photodynamic　therapy　(PDT)　relies　on　the　interaction　of　light,　photosensitizer,　and　the　presence　of　oxygen,　leading　to　cytotoxicity　to　the　tissue　containing　the　photosensitizer.　The　tissue　specificity　of　photosensitizer　is　thus　one　of　the　key　factors　in　photodynamic　therapy.　The　limited　targeting　capability　of　current　photosensitizers　that　are　in　the　clinical　applications　has　led　to　the　active　development　of　the　new　generation　of　photosensitizer.　Another　approach-peptide　conjugation-to　enhance　the　tissue　specificity　of　photosensitizers　were　reviewed.　The　cell　penetrating　peptides,　vasculature　targeting　peptides,　and　peptides　targeting　cell　surface　receptors　were　reviewed.　The　current　research　indicates　that　the　effectiveness　of　peptide　conjugation　to　confer　the　tissue　specificity　to　photosensitizers.