Background/Introduction: Cholinesterase (ChE) consists of a group of enzymes that hydrolyze choline esters. There are two ChE isoenzymes in blood: acetylcholinesterase (AChE; EC 3.1.1.7), also known as erythrocytes or true ChE, which is found mainly in red blood cells; and butyrylcholinesterase (BChE; EC 3.1.1.8), also known as plasma ChE or pseudo-ChE, which is present in plasma. Blood AChE or BChE activity would be selectively reduced by exposing them to poisonous chemical agents, insecticides