The determination of antiproliferative properties of compounds on tumour cells is important for assessment of their efficacy in cancer treatment. CFSE-labelled K562 cells were incubated with doxorubicin and ortho-or para-fluorosubstitute Schiff bases (compounds 1 and 2 respectively). CFSE intensities were analysed using flow cytometry. K562 cells treated with doxorubicin resulted in homogeneous high intensity fluorescence after 96 h of incubation. Schiff bases exhibited antiproliferative effects, but lower than doxorubicin. Our results reveal that CFSE assay can be used for determining in vitro antiproliferative features of anticancer drugs and/or compounds from herbal or chemical sources.