In the framework of an extensive health survey of viscose rayon workers in Belgium, 187 workers underwent a neuropsychological examination. Of these, 120 had been exposed for at least a year to carbon disulfide (CS&inf2;) and hydrogen sulfide (H2S), and 67 served as a non-exposed control group. Measurements showed that many of the 17 jobs in the factory involved exposures to CS&inf2; ranging from 3 mg/m(3) (centrifuge operator) to 147 mg/m(3) (spinning cake regulator), far in excess of the threshold limit value (TLV) of 31 mg/m(3); H2S exposures remained below the recommended TLV of 14 mg/m(3). The neuropsychological investigation included subtests of the Wechsler Adult Intelligence Scale, the entire Wechsler Memory Scale, the Bourdon-Wiersma Test, the Santa Ana Dexterity Test, the Gibson Spiral Maze, and the Bimanual Sinusoidal Movement Test. Specific questions were included to account for the effects of age, educational level, eye complaints, alcohol consumption, medication intake, and test motivation. Only the group exposed to values exceeding three times the recommended TLV for CS2; had significant impairments in both the speed and the quality of psychomotor performance. Exposure to CS2; and H2S had no significant effect on memory and attention. Covariance analysis revealed the confounding influences of educational level and eye complaints for explaining observed "differences" in memory and attention tasks found by univariate analysis.