Background/Aim: This study specifies a strategy to improve radiotherapy by partial synchronization of p53-deficient cancer cells (FaDu and H1299) in mitosis using taxol, with protecting p53 wild-type cells (A549) by the prior administration of cytostatic compounds. Cytotoxic and cytostatic effects of ionizing radiation, cisplatin, doxorubicin and taxol, administrated alone or in combination were investigated in vitro by flow cytometry. Results: A protective effect of doxorubicin but not cisplatin was found after administration of triple sequence with ionizing radiation and taxol. It was found that preliminary administration of doxorubicin induced growth arrest and protected A549 cells from the taxollradiation treatment, while simultaneously killing FaDu and H1299 cells. Conclusion: The proposed therapeutic strategy allows protection of p53 wild-type cells and selectively increases radiosensitivity of p53-deficient cancer cells.