The present study has the aim to describe morphologically, morphometrically and stereologically some changes in the tongue epithelium of rat fetuses under the effect of cyclosphosphamide. This drug was used in a single 6mg/kg according to the body weight in the tenth ­ pregnancy day while the control group received equal dosage of saline solution by the same duct and in the same day of pregnancy. The fetuses were plunged into fixed solution of Bouin for five days and the heads of then were divided and blocked in paraffin. Histological sections of six-micrometer thickness were performed and then colored with hematoxilin and eosin. It was used morphometrical and stereological analysis after the morphological study. The data were submitted under the statistical non-parametric test of Mann-Whitney. The results showed that the cyclosposphamide usage effect during the rat pregnancy caused a delayed in the embryo fetal growing, a reduction in the placental weight as wells as in the umbilicus cord length. The covering epithelia in the tongue of the treated group showed some changes since there was an epithelial hyperplasia associated with a cell hypotrophy. The fetuses in this group were more premature than the ones in the control