Severe acute poisoning of cypermethrin is rare. We report this case about a 47-year oldman who was brought to Emergency Room with drowsiness and drooling of saliva after intentional self-harm with 2.25 gram of cypermethrin. His initialcondition was stable. However, nine hours after admission, he developed seizures and reduced conscious level. He was ventilated overnight for airway protection. Management of acute severe poisoning is discussed in this case report.