Acrylonitrile monomer is used in the production of artificial fibres and resins. It has been used as a fumigant. Acrylonitrile has acute toxic effects for men and animals on over-exposure by inhalation of the vapor, dermal absorption of the liquid and oral intake. Symptoms in men are non-specific and predominantly related to the central nervous system, the respiratory tract, the skin and to the gastrointestinal tract. Severe acrylonitrile intoxication is followed by loss of consciousness, convulsions, respiratory arrest and death. The detailed investigation of a patient with complaints after chronic exposure demonstrates the necessity of objective neurophysiologic studies. Acrylonitrile has carcinogenic properties in animals. It is also embryotoxic and teratogenic. Epidemiological studies in men exposed to acrylonitrile are not convincing. There may be a slight excess of deaths from lung cancers and other malignant tumors. Effects of potential antidotes were studied in animal experiments. Rats were intoxicated with lethal doses of acrylonitrile by different routes of application. The cyanide antidotes 4-dimethylaminophenol plus thiosulfate showed some protective effect only after oral but not after i.p. or inhalational acrylonitrile administration. Of the sulfhydryl compounds cysteine, N-acetyl-cysteine, cysteamine and diethyldithiocarbamate, the two antidotes cysteine and N-acetylcysteine proved to be especially effective. From these experiments a tentative schedule of antidotal therapy for humans accidentally intoxicated with acrylonitrile is inferred, using N-acetylcysteine by analogy with the therapeutic regimen effective in cases of paracetamol poisoning.