Formerly, atropine was used as an antidote for alkylposphate poisoning. And in 1955 I. B. WILSON suggested PAM (2-pyridine aldoxime methiodide) as a specific antidote for alkylphosphate poisoning. In 1956 K. HIRAKI et al. introduced PAM in Japan. Since that time, the PAM therapy for alkylphosphate poisoning has been widely practised in this country. In recent years, as the fowls were frequently subjected to alkylphosphate poisoning in Okayama district, we had investigated therapeutic and preventive effects of PAM for alkylphosphate poisoning of fowl. The alkylphosphate used in this experiment was parathion (diethyl p-nitrophenyl thiophosphate) and the method we employed for determining the cholinesterase activity of serum was MICHEL's method. Hens and chickens of White Leghorn, Barred Plymouth Rock and Rock Horn were used in this experiment. The results we obtained were as follows. 1. The lethal doses of parathion for fowl were 4-6 mg/kg in chichen and 10 mg/kg in hen. 2. With intravenous injection of 100 mg/kg of PAM, within 20 minutes after oral LD of parathion, conditions of fowls remarkably recovered compared with controls. The administrations of PAM of same quantity were more effective when they were divided into two or three doses. Alkylphosphate poisoning caused no retained disturbance sin recovered chickens of which ovary not yet developed. 3. In the case of laying hens, even if PAM administration prevents them from death, they lose their economical value. Because, PAM cannot prevent hemorrhage in the ovary and ruptured yolk caused by the poisoning, and so poisoned hens cease the egg laying for following two or three months. 4. As a effective period of time of intravenously injected PAM is only one hour or so, we cannot expect too much of the preventive effect of PAM for alkylphosphate poisoning of fowl in the fields.