A variety of 1,8(11),15(18),22(25)- and 2,9(10),16(17),23(24)-tetra-substituted and 2,3,9,10,16,17,23,24-octa-substituted Zn(II) phthalocyanines, bearing dialkylaminophenoxy and trialkylammoniumphenoxy groups, have been synthesized, characterized and tested as photosensitizers against Staphylococcus aureus, Escherichia coli and Candida albicans. All phthalocyanines exhibited intense absorption bands in the phototherapeutically useful 670-700 nm region, with a molar extinction coefficient of the order of 105 M-1 cm-1. All derivatives bearing pos. charges showed a good photosensitizing efficiency (causing a greater than 4 log reduction in cell survival), as well as a high quantum yield for generation of singlet oxygen. Variations of the chem. structure appeared to strongly affect both the physicochem. properties and the phototoxic activities against microorganisms.