The effects of neurotoxins on human behavior are reviewed. Three ways in which behavioral effects of chemicals are measured are self reporting, observation by trained observers, and performance of structured tasks. Acute intoxication involves dizziness, confusion, lethargy, and motor incoordination. Subacute and chronic exposure affects memory and problem solving. Very few neurotoxins have known effects based on epidemiological studies. Some chemicals that have been studied include carbon-disulfide (75150), carbon-monoxide (630080), formaldehyde (50000), lead (7439921), mercury (7439976), and trichloroethylene (79016). Most epidemiological studies employ a battery of psychophysiological tests, which test intelligence, memory, coordination, reaction time, visual function, and alertness. Human laboratory investigations address behavioral effects of neurotoxins measured under acute, low concentration exposure conditions, simulating a work day. The author concludes that there is a need for research to study interactions among neurotoxins.