2-Demethoxy-2,3-ethylenediamino　hypocrellin　B　(EDAHB)　is　a　diamino-substituted　hypocrellin　B　(HB)　with　high　absorption　of　red　light　and　high　quantum　yield　of　both　singlet　oxygen　(O-1(2))　and　superoxide　anions　(O-2(center　dot-)).　Here　we　reported　the　cellular　uptake,　subcellular　location,　and　cytotoxicity　of　EDAHB,　as　well　as　EDAHB-mediated　photodynamic　therapy　(PDT)　efficiency,　and　cell　apoptosis.　Results　showed　that　EDAHB　accumulated　in　HeLa　cells　rapidly　up　to　1　h,　with　a　subsequent　decrease　in　the　rate　of　uptake.　EDAHB　distributed　with　well-defined　spots　throughout　the　cytoplasm　of　the　cells.　EDAHB　showed　a　much　higher　photopotentiation　factor　than　HB.　The　phototoxicity　of　EDAHB　to　HeLa　cells　occurred　via　a　mitochondria/caspase　apoptosis　pathway.　This　study　showed　EDAHB　to　be　a　promising　candidate　of　photosensitizer　for　anti-tumor　PDT.　(C)　2012　Elsevier　B.V.　All　rights　reserved.