The inhibitory effect of hydrated fullerene C60 (HyFn) and the sodium salt of the fullerene polycarboxylic derivative C60Cl (C6H4CH2COONa)5 on the formation of amyloid fibrils by X-protein in vitro has been studied by electron microscopy. It has been shown that these compounds not only destroyed mature amyloid fibrils but also prevented the formation of new fibrils. This property of fullerenes, nanoparticles, can be used for the development of a novel medicinal nanotechnology in the therapy of amyloidoses.