The review is devoted to the competitive blockers of different nicotinic acetylcholine receptors, α-neurotoxins from snake venoms, and α-conotoxins from marine snails of the Conidae family. The relationship between the structure and function of these toxins is discussed. Recent data on the mechanism of α-neurotoxin and α-conotoxin interaction with the nicotinic acetylcholine receptor are presented. © 1999 MAEe cyrillic signK "Hayκa/Interperiodica".