In the search for new derivatives of anthracycline antibiotics with the ability to overcome the drug resistance barrier, a series of new analogs of these antibiotics, containing the amidino group at C-3' position of the daunosamine moiety, have been synthesized. The new compounds were tested for their cytotoxic activity in vitro against the sensitive LoVo, MES-SA and HL-60 human cancer cell lines as well as their resistant sublines: LoVo/Dx, MES-SA/Dx5 and HL-60/MX2, respectively. The majority of these derivatives appeared to be able, completely or partially, to overcome the drug resistance barrier of cancer cells. The effect of structural modification on this ability was determined. The obtained results indicated that introduction of the amidino group into the daunosamine moiety of anthracycline molecules appears to overcome the drug resistance of cancer cells.