Аннотация:The paper presents results on the response of living HeLa cells in vitro to low-dose photodynamic treatment with Radachlorin photosensitizer. Quantitative monitoring of variations of optical and morphological parameters of cells was performed by means of digital holographic microscopy and assisted with observations in confocal fluorescent microscope. The statistical analysis of the results obtained demonstrated significant morphological changes of cells along with invariable dry mass. The AO/EB standard test validated cell membrane integrity and demonstrated cells rounding and membrane blebbing. These data allow us to assume apoptosis as a major pathway of cell death activated in our experimental conditions.