Cadmium in the air, drinking water and food has the potential to affect the health of people, mainly those who live in highly industrialized regions. Cadmium affects placental functions, can cross the placental barrier and directly disturbs fetal development. It is also excreted into milk. The organism is particularly susceptible to cadmium exposure at perinatal period. The effect on rat maxillary molar junctional epithelium a continuous exposure to drinking water containing low level of cadmium during lactation was studied. Female rats received drinking water ad libitum containing 300 mg/l CdCl2 throughout the whole lactation. Control animals received a similar volume of water without cadmium. Lactent rats (21 day-old) were killed by lethal dose of anesthetic. The heads were separated, fixed in an "alfac" solution for 24 hours; palate region was serially sectioned in frontal plane, at level of first molars. The sections, 6 µm-thick, were stained with hematoxylin and eosin. Nuclear epithelium parameters were estimated, as well as cytoplasm and cell volume, nucleus/cytoplasm ratio, numeric and surface density and epithelial thickness. Mean body weight was 34.86 g for the control group and 18.56 g for the treated group. Histologically, the epithelium was thinner, with more numerous and smaller cells. In this experiment, cadmium induced epithelial hypotrophy, indicating a direct action in oral mucosae cells, besides retarded development in pups