PDT is an establi shed cancer treatment modali ty , This can be attributed to the attractive basic concept of PDT; the combina ti on 0[' two ther a peut ic agents, a photosensitizing drug and light, which are r elatively harmless by themselves but combined ultimately ca use more 0 1' less selective tumor destruction, The bacteriochlorophyll - derivatived photosensitizers are known to be s ta ble and hi ghly efficient‘ In this s tudy, we conducted a series of experiments to develope the ligh t induced anticancer drugs against oral cancer cell ‘ We tested the cytotoxicity of the hydroxybact eriochlorine by MTT a ssay and observed the cell death pattern (apoptosis or necrosis) after PDT by hoechst 33342 and propidium iodide s taining methods , IC50 value of the hydroxybacteriochlorine was 31,3ngjm.Q, At higher doses of hydroxybacteriochlorine () 60 ng/ 뼈) , cancer cells died exc lus ively by nec rosis after PDT By contrast, at IC50 value, h ydroxybacteri ochlorine in duced ca ncel' cell to undergo a poptotic cell death The induction begins approximately 6 hours after PDT We investigates int racellu la r localizati on of hydroxybact eri ochl orine by ora l cancer cell via confocal laser scanning microscopy, Oral can cer cells dual-stained with hydroxybactel' iochlorine and organelle-specific fluoresc ence probes (Mi totracker, Lysotracker , ER- Trac ker) revealed an int l'acellula l' flu orescence distribution restrict ed to cytoplasmic compartments with no detectable fl uoresce nce in the nucleus Confocal images of cells containing hydroxybacteriochlorine were never overlap to mi tochondria, lysosome, endoplasmic l'eticulum when digitally overlapped with the organelle-specific flu orescence probe images of the same cells , These resul ts demonstrat ed that the hydroxybacteriochlorine may have a function as a photosens it izer and cytotoxicity hydroxybactel' ioc hlorine for oral ca ncer cell is more sensitive than head & neck cancer cell or cervical cance l' cell Ther efore PDT using hydroxybact eriochlorine is suitable treatment for oral cavity car cinoma patients.