Background and Design.- We present electrophysiological features of neuropathy due to chronic exposure to different organic hydrocarbon derivatives (toluene/methyl benzene and n-hexane) that are known to be neurotoxic. Twenty-five subjects who abuse toluene by sniffing and 29 subjects who have been exposed to n-hexane by way of inhalation and skin contact have been included in the study. None of the subjects who abused toluene for an average of 3 years had any complaint. Ten subjects with exposure to n-hexane were asymptomatic, however 19 patients had symptoms of varying severity. The mean exposure time to n-hexane was 32.3 months, and 28 months in the groups of subjects with and without symptoms respectively. Electroneuromyographic examination was performed in these patients.Results.- Mild sensorymotor polyneuropathy was detected in 12% of subjects in the toluene group, and 60% of subjects in the asymptomatic n-hexane group. Neurological examination disclosed predominant central nervous system involvement in subjects with exposure to toluene. Motor and less severe sensory polyneuropathy of moderate to severe degree was noted in all of the patients in the symptomatic n-hexane group. Involvement of myelin component was more prominent in the adult patients with longer period of exposure to n-hexane.Conclusion.- We propose that n-hexane eads to predominantly peripheral nervous system damage, whereas toluene leads to central nervous system involvement.* Anahtar Kelimeler: Toluen, n-Heksan, Polinöropati*Key Words: Toluene, n-Hexane, Polyneuropathy.