The article reveals that a considerable amount of information on the effect of pesticides on man is available from use experience, from human poisoning cases, and from volunteer studies. It appears that more attention should be paid to obtaining toxicological information based on use experience associated with workmen occupationally exposed or residents living in proximity to pesticide-treated areas. Previous study has shown that many occupationally exposed workers suffered exposures of magnitudes which could not be safely applied to volunteers. However, studies must also be carried out on volunteers in order to obtain information based on accurately known dosages. Information is particularly lacking on the possible long-term effects of small, repeated doses of pesticides on man.