The effect of nickel nanoparticles (NiNPs) on the bioaccumulation of essential and toxic chemical elements in the organs of rats after oral administration is evaluated. Wistar rats receive Ni in the form of a soluble salt (basic Ni carbonate) or two types of NiNPs with average diameters of 53.7 and 70.9 nm in doses of 0.1, 1.0, and 10 mg/kg body weight in terms of nickel for 92 days in the composition of the diet consumed. The content of Ni as well as Ag, Al, As, B, Ba, Be, Ca, Cd, Ce, Co, Cr, Cs, Cu, Fe, Ga, Gd, K, La, Mg, Mn, Na, Pb, Rb, Se, Sr, Tl, V, and Zn is determined in the liver, kidneys, and spleen by inductively coupled plasma mass spectrometry. The content of Ni in the kidneys and brain increases under the influence of both the salt and NPs; in the liver and gonads, only after the introduction of the salt form, but not with NPs; in the spleen the level of Ni does not increase upon the intake of all Ni forms. In rats receiving NiNPs various changes are observed in indicators of trace-element homeostasis, including the increased bioaccumulation of Pb in the liver, gonads, and brain, As in the spleen, and Al in the liver and brain; inhibition of the accumulation of Mg, Mn, and Sr in the kidney and Ba in the kidneys and spleen. The content of Ca under the influence of NPs increased in the kidneys, but decreased in the gonads. A number of effects arising from the administration of Ni in the nanoform to animals are absent or have the opposite sign in the case of salt-form administration. NiNPs have little effect on the bioaccumulation of Cu, Fe, Zn, Se, Mg, and K. The effects demonstrated by the administration of NiNPs to animals can be considered as manifestations of nanometallomic patterns, i.e., processes mediated by changes in the gene expression of metalloproteins caused by NPs or products of their biological transformation.