Nucleosome positioning is an important modulator of gene regulation in normal and diseased cells and can be considered as a valuable marker for diagnostics in liquid biopsies based on cell-free DNA (cfDNA). cfDNA originates from genomic DNA regions protected from digestion by nucleosomes, and therefore it is possible to use it to understand disease-specific changes in nucleosome positioning. Our lab is developing so-called "nucleosomics" analysis approaches for the purpose of liquid biopsies. We have generated high resolution nucleosome maps in cancer and normal cells and cfDNA from blood plasma. In this talk I will focus on our recent projects on this type, devoted to leukaemia, breast cancer and glioblastoma. We analysed cancer-specific local nucleosome repositioning as well as changes in integral characteristics of chromatin organisation and investigated molecular mechanisms of such changes. I will also describe our more recent results on nucleosome repositioning during ageing.