The purpose of this study was to examine the effect of low level benzene exposure on neurobehavioral functions, AChE in blood and brain, bone marrow picture in Kunming mice. Forty adult Kunming male mice were divided into 4 groups. They were exposed to 12.52, 3.13, 0.78 and 0 ppm benzene for 2 h.d-1 for 30 d. Central nervous system (CNS) function was inhibited by 12.52 ppm and excited by 0.78 ppm benzene exposure, but irregularly affected by 3.13 ppm. AChE in blood and brain was decreased in 12.52, 3.13 ppm group. The weight of liver to body weight ratios in 12.52 ppm group was higher than those of control group significantly. Bone marrow picture revealed inhibited proliferation of white and red cell systems, especially in 12.52 ppm group, consisting of decrease of percentage of myeloblast, premyelocytes, myelocytes, erythroblasts and megakaryocytes, especially in 12.52 ppm group.