Human neurobehavioral toxicology testing was reviewed and discussed. Rationales for developing neurobehavioral test batteries were discussed. Two approaches have been developed. One assessed all major nervous system functions in order to identify all potential problems that could be caused by chemical exposures and the other measured neurotoxic effects that usually resulted from environmental or occupational exposures. Neither approach has been followed exactly in practice. Four human test batteries that were based on past research findings which utilized elements of both approaches have been developed: a battery developed by the Finland Institute of Occupational Health (FIOH) for screening workers, a problem based approach used by NIOSH and other researchers, a World Health Organization (WHO) recommended approach, and a computer implemented neurobehavioral evaluation system (NES) developed by researchers in the United States. Target organ effects identified by NIOSH and the American Conference of Governmental Industrial Hygienists were discussed. These have led to a list of 35 effects produced by at least 25 of 750 chemicals known to affect the nervous system. The ability of the test batteries to assess target organ effects was discussed. The WHO, FIOH, and NES test batteries are expected to be able to assess most of the effects of neurotoxic agents; however, some forms of peripheral neuropathy and affective symptoms, weakness, ataxia, and sensory effects would be missed by the batteries. Methods for improving the WHO, FIOH, and NES batteries were discussed.