A case of intoxication with Phytosol (an insecticide) in a 29-year-old man is described. Ingestion of Phytosol (suicide attempt) produced signs of cholinergic crisis followed, after 16 days, by features of peripheral neuropathy and later, with the regression of signs of polyneuropathy, gradually increasing spastic paralegia. Electrophysiological investigation of nerves which were clinically moderately involved demonstrated sparing of sensory fibers and damage to motor fibers. There was no change in maximal motor conduction velocity. Histology of the clinically involved sural nerve revealed axonal changes together with demyelination, presumed to be secondary in type. This case shows that the susceptibility to delayed nervous system damage in man is greater than it might be expected from experimental studies and calls for caution in human exposure to these compounds.