Pregnant rats were divided into three groups. Two groups are exposed to manganese from drinking water contaminated with manganese in 10 and 2 g/L respectively. Cerebral development of the offspring of rats was studied. The results are as follows. (1) The thickness of frontal and parental cortex of high dose Mn-exposed groups was significantly reduced, but glial fibrillary acid protein (GFAP) and the densities of its products were increased. (2) Cingular cortex was thickened, GFAP and the density of its products of cingular cortex was increased in both Mn-exposed groups compared with the control group. (3) The area, GFAP and the densits of its products of corpus callosium in the high Mn-exposed group were significantly increased compared with those in both low Mn-exposed and control groups.