Phenytoin (diphenylhydantoin, dilantin) has been the chosen anti-convulsive for the treatment of sudden disorders since the late 1930's. Several epidemiological and clinical studies in human beings showed an increase in malformations in descendants of which mothers took phenytoin during gestation, such as cranio-facial development and growth abnormalities, distal phalangeal hypoplasia, and light or moderate mental deficiency. This work had the goal to study the lingual mucosa, under histopathological and morphometric standpoints, in rat fetuses which were given an intraperitonial injection, consisting of a unique dose of phenytoin (70 milligrams/kilogram of their weight). Being that, we included the examined material in paraffin, 6 micrometers thick, and also colored these incisions using hematoxylin and eosin. The morphometric parameters were estimated using drawings (50 sketches) made on paper and then measured using a millimetric scale, obtained with the aid of a light camera JENA, with final magnification 1000X. The statistical confrontation was performed employing Mann-Whitney non-parametric test. The results showed that the average body weight of treated animals decreased. Histopathological and morphometric changes at all lingual regions were observed