. Cucurbiturils are a family of macrocyclic oligomers capable of forming host-guest complexes with various molecules. Due to noncovalent binding to drug molecules and low toxicity, cucurbiturils has been extensively investigated as a potential carrier for drug delivery. However, the immune system interactions with different drug carriers, including cucurbiturils, are still under investigation. In this study, we focused on cucurbiturils immunosafety and immunomodulation properties in vivo. We measured blood counts, lymphocyte subpopulations in blood, spleen, and bone marrow, and assessed in vivo toxicity to spleen and bone marrow cells after intraperitoneal administration to mice. We also evaluated the effect of cucurbiturils on cellular and humoral immune responses. Cucurbiturils in high concentrations effect on the immune system in vivo. The action of various cucurbiturils differs in different homologues, which, apparently, is associated with different interactions in the internal environment of the body.