Allylic compounds exert direct genotoxic activities which depend on the chemical nature of the leaving group and on further substituents. Besides the direct genotoxic effects, metabolic activation mechanisms are also conceivable. Epoxidation seems to play a minor role in bioactivation, whereas the metabolic formation of strongly mutagenic alpha, beta-unsaturated carbonyl compounds is obviously of great importance for the indirect genotoxicity of allylic compounds. Only in the case of 2,3-dichloro-1-propene is an epoxide formed which is extremely unstable and immediately rearranges to the strong mutagen, 1,3-dichloroacetone.