The reactions of dermal structures to subcutaneous injections of gold nanoparticles were studied in CBA mice. Routes of the nanoparticles migration after injection and the mechanisms of their effects on the adjacent tissues were studied. Injected nanoparticles were phagocytosed by macrophages; some of them migrated to lymphoid follicles of the lymph node, while others migrated into blood vessels, where the particles were released from the macrophage cytoplasm into circulating blood. The endothelium was destroyed as a result of the toxic activity of macrophages loaded with nanoparticles. Two mechanisms of angiogenesis inhibition and death of blood vessels in tissues after injection of nanoparticles were distinguished. One mechanism consisted in deactivation of macrophages producing vascular endothelium growth factor inducing the formation of endothelium in the growing blood vessels, but not in direct inhibition of this factor. The other mechanism was realized through direct death of the endothelium in migration of macrophages through the vascular wall.