Computerized neurobehavioral tests are being used increasingly in occupational and environmental health to measure potential effects of exposure to neurotoxicants. Many factors affect performance on these tests. Data sets from application of a computerized neurobehavioral evaluation system in epidemiologic investigations of two occupational groups, printing pressmen and construction painters, were analyzed. Age and education were the major covariates of performance in these groups. The reliability of these computerized tests was also reviewed. Computerized neurobehavioral tests are similar to conventional tests in terms of reliability and relationships to known covariates.