The comparative accumulation of fluorescein Na2-salt (FINa) by the established cell lines of human tumors (cancer of the uterine body, urinary bladder, Wilms tumor, chorionepithelioma, melanoma, rhabdomyosarcoma, osteosarcoma) and human normal fibroblast cultures was obtained. The tumor cells of the different genesis is characterized by its own parameters of FINa accumulation. The most pronounced accumulation of dye has been noted for cells of cancer of the uterine body, the urinary bladder and chorionepithelioma. The normal cells accumulated FINa less considerably. Mechanism of the selective accumulation of dye by the tumor cells was discussed.