In order to evaluate the confounding factors of neurobehavioral tests and the neurobehavioral effects in the workers exposed to organic solvents, NCTB was carried out on 100 workers. 46 workers had never been exposed to neurotoxic substances, and the others were being exposed to the solvents, mainly toluene. Simple reaction time, digit symbol, Santa Ana dexterity test and persuit aiming were different with age in non exposure group. Simple reaction time was carried out well in males, and digit symbol and persuit aiming were in females. There was no difference at educational level when the subject was educated over 12 years. Santa Ana dexterity and Benton visual test differed according to exposure level to toluene, however simple reaction time didn't. The acute neurotoxic effect was not excluded in this study. But, NCTB could be used to evaluate and prevent neurobehavioral changes in workers exposed to neurotoxic solvents in Korea.