Rhesus monkey fetuses were inoculated with Venezuelan Equine Encephalitis (VEE) vaccine virus by the direct intracerebral route at approximately 100 days gestation to determine possible teratogenicity of the virus. Congenital micrencephaly, hydrocephalus and cataracts were found in all animals and porencephaly in 67 percent of the cases. The virus replicated in the brain and other organs of the fetus. VEE vaccine virus is teratogenic for non-human primates and must be considered a potential teratogen of man.