Organophosphates (OP) are irreversibly bound to cholinesterase, causing deactivation of acetylcholinesterase. As a result of inhibition of plasma cholinesterase, increased sensitivity to drugs hydrolyzed by this enzyme can occur, e.g. succinylcholine and mivacurium. A case of more prolonged succinylcholine-induced paralysis in a child with undiagnosed acute OP insecticide poisoning is presented. A 7-h period of apnea and paralysis after administration of succinylcholine was attributed to the decreased rate of succinylcholine metabolism resulting from inhibition of pseudocholinesterase by the insecticide. In seven previously reported cases of prolonged succinycholine apnea after OP poisoning, exposure to insecticide was in chronic or subacute form without any obvious symptoms, and the duration of apnea did not extend up to 4 h, whereas in our case with acute, severe poisoning, succinylcholine led to more prolonged muscle paralysis. In the anesthetic management of patients with acute OP poisoning, succinylcholine should be avoided.