Parathion is distributed equally in the poisoned human bodies, as it has been in the case of experimental animals, and disappeared after 24-48 hours. This may be attributed to the splitting of parathion both p-nitrophenol and diethyl (thio) phosphate. The most part of p-nitrophenol is excreted in the urin within 1-2 days and only a part of it prolonged into a week accompaniing no sign of poisoning. It is said that diethyl (thio) phosphate is excreted similary, but poisonus (1/4-1/5 of parathion) for the human bodies and animals. The splitting above mentioned is based on the enzym action, including cholinesterase which is found in the animal sera and organ extracts. The parathion splitting action of serum is inhibited in the case of various kinds of disease.