Fullerenes are a relatively new group of compounds and represent a class of sphere-shaped molecules made exclusively of carbon atoms. Since their discovery in 1985, many aspects of both fullerene and its analogues have been intensively studied to reveal their physical and chemical reactivity, as well as potential use in biological systems. Both in vitro and in vivo studies have shown that polyhydroxylated fullerene derivatives, fullerenol nanoform (C60(OH) n , n = 2-72), can be potential antioxidative agents in biological systems. This chapter represents a review of published studies of fullerenes' biological activities with special accent on the most tested fullerenol nanoform C60(OH)24.