The template activity, nucleosomal pattern and thermodenaturation parameters of transcriptionally low active (TLA) and transcriptionally active liver chromatin fractions were studied in adult (6–8 months) and old (26–28 months) rats. The following age-related changes of chromatin template properties were found: decrease of endogenous DNA polymerase α- and β-activity in vitro in both chromatin fractions, and redistribution of newly synthetized RNA between mono- and oligonucleosomes in the TLA fraction. These changes are thought to be connected with age-related reorganization of chromatin structure, i.e. with increase of DNA-protein interactions, which stabilize association of chromatin supranucleosomal structures.