Incorporation of labelled precursors into total and nuclear DNA of liver tissue was inhibited after administration into animals of eserine at a dose 0.1--0.2 mg/100 g of body weight. Simultaneously, DNAase activity was increased and cholinesterase activity was inhibited in liver tissue. The DNA synthesis was inhibited in liver slices, if they were incubated with 2.10(-6) M eserine. The DNAase activity was unaltered in vitro. A cholinolytic compound metacin, pre-administered into the animals, was ineffective at dose of 1 mg/kg; it slightly decreased the effect of eserine at dose of 0.25 mg/kg.