The apoptotic index, cell cycle progression and caspase-3 activation in K-562 cells induced to differentiate by DMSO or quercetin have been studied. Quercetin treatment of K-562 cells was accompanied by cell cycle arrest in G2/M and apoptosis with caspase-3 activation. In contrast, DMSO-induced differentiation was accompanied by the complete cell cycle arrest in G1/G0 with negligible caspase-3 activation. In spite of the appearance of benzidine-positive cells and the decreased CD71 level in K-562 cells after exposure to quercetin, the analysis of 1H NMR spectra revealed the overall balance in favor of apoptosis, namely the increase in the content of NMR-visible mobile lipid domains and the decreased intensity of choline-containing metabolites.