Induction of conjugation by chemical agents was studied in nine species of Paramecium. KCI + acriflavine + Ca-poor conditions were effective in inducing conjugation in P. caudatum, P . multimicronucleatum, P. aurelia, P. jenningsi and probably in P. h'ichium. KC1 + Ca-poor conditions were effective in P. caudutum, P . traunsteineri and probably in P. hichiurn. KC1 f acriflavine + Ca-poor conditions were also effective in inducing interspecific conjugation. Interaction between complementary mating types is not involved in the chemical induction of conjugation, but otherwise chemically-induced conjugation is, in at least some pairs, essentially identical to normal conjugation induced by the interaction between complementary mating types. The mechanism of induction of conjugation and applications of chemical induction of conjugation to genetic studies are discussed.