Trigeminal somatosensory evoked potentials (TSEP) were studied in 33 workers manipulating trichlorethylene for 3 to 22 years and in 33 control subjects. A significant excessive latency delay of N13, P17 and N45 waves in workers was found. Evoked potential abnormalities found in 15 exposed subjects (45%) were as following: excessive latency delay in 9 cases (27%), decrease of amplitude in 2 cases (6%) and asymmetrical responses in 4 cases (12%). Among 5 workers (15%) presenting clinical abnormalities of trigeminal nerve impairment, only one had normal evoked potential. TSEP were altered in 11 workers (33%) who had no clinical impairment. We suggest that TSEP should be confirm trigeminal impairment in chronic cases of workers exposed to carbon tetrachloride and to predict infraclinic lesions.