Vitamin A (0.2 mu gr, 0.6 mu gr, 1.2 mu gr) was administered orally to the mice on days 8-11 of gestation. Fetuses were removed on day 17 of gestation. No external malformation of the fetuses was seen on the stereomicroscope investigation. Corneal degeneration was seen on the light and electron microscopic examination. As a result it was accepted that vitamin A taken during the critical periods of gestation affected the development of cornea.