Seven　emodin　quaternary　ammonium　salts,　two　aloe　emodin　quaternary　ammonium　salts,　one　water　soluble　emodin　quaternary　ammonium　as　well　as　a　quaternary　ammonium　salt　of　a-naphtholbenzein　were　synthesized　and　the　in　vitro　anticancer　activities　were　tested.　Emodin　quaternary　ammonium　salts　containing　one　long　carbon　chain　showed　very　low　anticancer　activities,　and　emodin　and　aloe　emodin　quaternary　ammonium　salts　containing　two　carbon　chains　exhibited　high　anticancer　activities.　Using　hydrophilic　long　chains　to　replace　lipiophilic　long　carbon　chains　made　emodin　quaternary　ammonium　salts　lose　anticancer　activities.　Quaternary　ammonium　salt　of　a-naphtholbenzein　showed　a　moderate　anticancer　activity,　which　indicated　that　the　introduction　of　lipiophilic　cations　to　a　molecule　with　ability　to　transfer　electrons　could　increase　its　:anticancer　activity.