The oral administration of gold nanoparticles at dose 190 mg /kg animal body weight during 8 days leads to changes in the cellular composition of the mesenteric lymph nodes, the severity and reversibility of the reaction was determined by the size of gold nanoparticles. The cellular composition of the lymph nodes after the introduction of gold nanoparticle size of 1-3 nm for 8 days corresponded the control values, indicating the absence of immunotoxicity. Duration of recovery of cellular composition of the lymph nodes after administration of gold nanoparticles with size 15 nm and 50 nm does not exceed 21 days. It can be concluded that 15 nm and 50 nm nanoparticles have no immunotoxic action at oral administration.