We have been studying some properties of the new generation photosensitizers--phthalocyanines. The influence of the certain phthalocyanine concentrations at combination with laser irradiation doses (semiconductor laser, lambda = 670 nm, P = 50 mW) have been studied by in vitro fluorescent methods. Cytotoxicity assay LIVE/DEAD for fluorescence microscopy and measurements of cells viability with multi-well plate scanner was used. The optimal phototoxic effect on MCF7--mamma carcinoma cells was observed 8 micrograms/ml ZnPcS2, 10 micrograms/ml ClAlPcS2 in combination with laser irradiation 50 J/cm2 and 100 J/cm2 respectively. This concentration and dose killed MCF7 carcinoma cells.