A case of parathion poisoning has been reported; in which the symptoms of hypoxia resulted from partial airway obstruction, however this was mistaken for parathion poisoning, and the correct diagnosis was proved by removal of hard blood clot in the bronchial bifurcation. Conclusions were as follows: Adquate administration of PAM and atropine presented impressive response of symptoms. 2. Careful and frequent removal of secretion might be the most important problem especially in this poisoning. 3. Massive administration of antibiotics could prevent pulmonary complications. 4. Pulmonary edema, the most common complication, was not present.