The effect of nanocluster iron-molybdenum polyoxometallates (POM) on the content of histone proteins and heat shock proteins in rats’ blood and liver after the single and repeated administration has been investigated. It was found that the introduction of POM was not accompanied by adecrease in the number of histone proteins in blood lymphocytes, which may indicate a lack of gene expression of pro-inflammatory factors. An increase in the content of the heat shock protein Hsp60 and Hsp70 in the liver was revealed, and the degree of increase depended on the nanoparticles exposition. The assumptions about the absence of a lymphocytes pro-inflammatory phenotype and the heat shock proteins protective effect were confirmed with the continuation of normal functional state liver parameters during all periods of polyoxometallates exposure.