Background: Formaldehyde (FA) is an economically important chemical that is commonly used in the production of industrial, laboratory, household, and cosmetic products. FA is a potential carcinogen and mutagen. Exposure to formaldehyde is common especially among medical and paramedical personnel as it is widely used disinfectant. The exposure becomes maximal and semi-obligatory among workers and personnel of anatomy departments in the different faculties of medicine in a lot of countries and Egypt among; it is the main substance used for cadavers and human parts preservations. Workers and staff of anatomy departments among those with the highest possible formalin exposure with the risk to experience part or most of its possible serious hazardous health effects. This attracts our attention and necessitates a careful study for the possible effects of formalin on the embryos of exposed mothers. Objectives: This study was designed to evaluate the teratogenicity of formaldehyde in experimental animals exposed to FA. Methods: The study included fifty adult female albino Mice, that were divided into five groups ; (Ia): Negative control group received distilled water, (Ib): Positive control: received oral colchicines 2mg/kg /day on gestational days 6-13, Group II, III and IV: received formaldehyde orally in gestational days 6-13 with concentrations 7,14 and 21 mg/kg/day respectively. Pregnant females were sacrificed on 18 th gestational day. The uterine horns were examined for resorption sites, alive or dead fetuses. Extracted fetuses were examined for external developmental abnormalities and stained for skeletal malformations. Results: Decrease in the body weight of the newborns, Increase frequency of abortion and Fetuses mortality and there were some anomalies among the newborn mice which included umbilical hernia, subcutaneous bleeding , ear deformity, delayed ossification of skull bones and Caudal vertebrae were unossified or showed very small ossification centre. Conclusion:The pervious findings suggest that formaldehyde is a teratogenic substance.