In　order　to　elucidate　the　mechanism　of　cytotoxicity　photoinduced　by　2-ethanolamino-2-demethoxy-17-ethanolimino-hypocrellin　B　(EAHB),　a　derivative　of　hypocrellin　B　(HB),　cellular　uptake,　subcellular　localization　as　well　as　photodynamic　therapy　(PDT)　efficiency　of　EAHB,　and　cell　apoptosis　photoinduced　by　EAHB　were　investigated　in　HeLa　cells　by　laser　confocal　fluorescence　microscopy,　3-(4,5-Dimethylthiazol-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium　bromide　assay,　flow　cytometry,　DNA　fragmentation　on　agarose　gel,　and　Western　blot.　The　results　showed　EAHB　was　distributed　throughout　the　cytoplasm　of　the　cell,　with　no　detectable　penetration　into　the　nucleus.　The　proportion　of　dead　cells　increased　with　increases　in　both　the　dosage　of　light　and　the　concentration　of　EAHB.　Its　phototoxicity　to　HeLa　cells　proceeded　via　apoptosis.　The　EAHB-PDT　treatment　induced　a　cytochrome　c　release　from　the　mitochondria　into　the　cytosol　followed　by　the　activation　of　both　caspase　3　and　caspase　9　in　HeLa　cells.　The　results　suggested　that　EAHB-PDT　treatment　induced　apoptosis　in　HeLa　cells,　and　the　cellular　apoptosis　involved　a　mitochondria-/caspase-dependent　mechanism.