In　this　study,　two　novel　boron　dipyrromethene-based　photosensitizers　(BDP3　and　BDP6)　substituted　with　three　or　six　trifluoromethyl　groups　have　been　synthesized　and　characterized　with　various　spectroscopic　methods,　and　their　photo-physical,　photo-chemical,　and　photo-biological　properties　have　also　been　explored.　The　two　photosensitizers　are　highly　soluble　and　remain　nonaggregated　in　N,N-dimethylformamide　as　shown　by　the　intense　and　sharp　Q-band　absorption.　Under　red　light　irradiation　(lambda　=　660　nm,　1.5　J/cm(2)),　both　photosensitizers　show　high　and　comparable　cytotoxicity　towards　HepG2　human　hepatocarcinoma　and　HeLa　human　cervical　carcinoma　cells　with　IC50　values　of　0.42-0.49　mu　M.　The　high　photocytotoxicity　of　BDP3　and　BDP6　can　be　due　to　their　high　cellular　uptake　and　low　aggregation　tendency　in　biological　media,　which　result　in　a　high　efficiency　to　generate　reactive　oxygen　species　inside　the　cells.　Confocal　laser　fluorescence　microscopic　studies　indicate　that　they　have　superior　selective　affinities　to　the　mitochondria　and　lysosomes　of　HepG2　and　HeLa　cells.　The　results　show　that　these　two　trifluoromethyl　boron　dipyrromethene　derivatives　are　potential　anticancer　agents　for　photodynamic　therapy.