Introduction: Sodium valproate is an anti convulsant drug which has been used to treat epileptic patients for last decades. Even a pregnant patient has to use this drug for the treatment of epileptic seizure. The purpose of this investigation is to study the effect of this medicine on the embryo in the mouse. Materials and Methods: Eight pregnant mice were given 200 mg/kg (i.p.) of sodium valproate on the day of gestation at three times intervals at 0,6 and 12 hrs. The control group consisted of seven pregnant mice which were injected sterile distilled water. On day 18 of gestation, all the embryos from both groups were removed, cleared and stained with Alizarine Red and Alcian Blue. Results: The embryos of the experimental group had an increase in the number of cartilage particles of vertebral body, adhesion of vertebral bodies, variability of the numbers of the ossification centers and the adhesion of the lateral ossification centers. Also spina bifida occulta was seen.\par Conclusion: Administration of sodium valproate to pregnant mouse can induce a variety of vertebral abnormalities including spina bifida occulta.