An 89-year-old man attempted suicide by ingesting a pesticide (trichlorfon). After surviving the initial critical period in the intensive care unit, he developed rapidly progressive distal weakness and sensory disturbance. Electrophysiological examinations revealed sensory motor axonal polyneuropathy. Delayed polyneuropathy is a rare manifestation of organophosphate poisoning. Nerve conduction studies play an important role in the diagnosis of this rare clinical condition.