Data on the reactions involving the addition of dithiocarboxylic, dithiocarbamic, and other heterosubstituted dithio-acids to compounds with a multiple bond are surveyed. It is shown that the character of the addition depends on the nature of thedithio-acid: dithiocarbamic and xanthic acids add via an ionic mechanism, while for dithiocarboxylic acids there is a possibility also of radical addition as well as cycloaddition together with the ionic addition.The bibliography includes 126 references.