Selol is a mixture of selenitetriglycerides synthesized from sunflower oil. As it contains the element selenium in its structure, it is suspected to exhibit chemopreventive and anticancer activity. In this study, the ability of Selol to inhibit cell proliferation and to induce apoptosis was investigated. Three cell lines were used: leukemia HL-60 cell line and multidrug-resistant HL-60/Dox (resistant to doxorubicin) and HL-60/Vinc (resistant to vincristine). Selol was shown to reduce the cell number as a result of treatment with increasing concentrations. For selected concentrations the evidence of apoptosis (changes in mitochondrial potential and caspase activity) was investigated, as well as changes in lysosome distribution. The study has shown that Selol overcame the cell resistance, as doxorubicin-resistant cells were more sensitive towards Selol than sensitive cells.