There was investigated the dynamics of 1-, 3- and 6-month exposure to 4 doses of silver nanoparticles of size 14.3 +/- 0.05 nm stabilized with gum arabic, and 4 doses of silver sulfate on the liver of male outbred rats by 13 cell morphofunctional indices. As the solvent to obtain a working solution there was used distilled water solutions of different conccentrations were obtained on the base of Moscow tap water cleaned out by a charcoal filter. The animals had free acccess to the drinkers with the studied water. For silver sulfate as a control intact rats served, for silver nanoparticles--acacia gum. The increase in the number of polyploid hepatocytes, micronekroses and discomplexation of hepatic beams and the decreasing the number of reticular endothelial system cells in the liver were shown to permit to evaluate the effect of 6-month nanosilver exposure to the liver at a dose of 0.3 mg/kg as pronounced harmful (Fel), 0.023 mg/ kg--as LOAEL, and 0.0028 and 0.0006 mg/kg--as NOEL. The effect of silver sulfate in doses of 0.28 and 0.03 mg/ kg is assessed as pronounced harmful (Fel), 0,0028 mg/kg--as LAOEL and 0.0005 mg/kg--as NOEL. More earlier detection of toxicity of silver sulfate as Fel (at 3 months) and in smaller doses indicates its greater toxicity to the liver than silver nanoparticles.