Two　novel　axial-disubstituted　silicon(IV)　phthalocyanines　(compounds　1　and　2)　have　been　prepared　by　introducing　paracetamol　(a　common　antipyretic　analgesic)　or　its　isomer　4-hydroxyphenyl　acetamide　at　the　axial　positions　of　silicon(IV)　phthalocyanine,　respectively.　Their　photophysical　and　biological　properties　have　been　examined.　Both　compounds　are　highly　soluble　and　exhibit　very　similar　absorption　spectra　in　N,　N-dimethylformamide,　which　is　typical　for　non-aggregated　phthalocyanines.　Both　compounds　are　photocytotoxic　against　HT29　human　colon　adenocarcinoma　cells.　Compound　2　shows　a　very　high　in　vitro　photodynamic　activity,　with　the　IC50　value　down　to　15　nM.　In　contrast,　compound　1　exhibits　a　much　lower　in　vitro　photodynamic　activity　toward　HT29　cells,　which　can　be　attributed　to　its　higher　aggregating　trend　in　the　biological　medium　and　lower　singlet　oxygen　quantum　yield.