Although the labor inspection had disclosed considerable exposure to carbon disulfide (CS&inf2;) in a Belgian viscose rayon factory, the company medical officer had not diagnosed any case of polyneuropathy in association with CS&inf2; exposure, although this finding had been extensively reported in the literature. Personal monitoring of CS&inf2; exposure was performed in 17 jobs. Because the working conditions in the factory had not changed since 1932, a CS&inf2; cumulative exposure index (CS&inf2; index) could be calculated for each individual. Examination of the exposed subjects (n = 111) included a self-administered questionnaire, a clinical neurologic examination, and electroneuromyography. Seventy-four workers from other plants, not exposed to CS&inf2; or to any other neurotoxic agent, served as referents. The average CS&inf2; exposures of the study group ranged from 4 to 112 mg/m(3). The data were analyzed with multiple regression methods, adjusting the effect of exposure for a number of possible confounders. Significant associations were found between the cumulative CS&inf2; index and symptoms consistent with polyneuropathy in the legs and with abnormal recruitment pattern and decrease of motor conduction velocities of the peroneal nerves. Exposures to CS&inf2; at levels below the present threshold limit value (31 mg/m(3)) were associated with significant decreases of motor conduction velocity.