Mercury and its compounds have a wide spectrum of toxicities depending upon the chemical forms and modes of exposure. Among the various chemical forms, mercury vapor and methylmercury are well known and established as neurotoxic agents. Since the disasters in Minamata and Iraq, in which fetuses were more susceptible than adults to methylmercury exposure, much attention has been focused on prenatal exposure to mercury and its consequence. Recently postnatal effects of in utero exposure to methylmercury through fish (and marine mammals) consumption by mothers have been concerned and several epidemiological studies have been conducted. Therefore, one of the most seriously concerned issues is the postnatal effects of in utero exposure to methylmercury. Because of these observations in humans, animal experiments have been conducted employing prenatal exposure to low levels of mercury. This paper reviews the animal (rodents) experiments concerning “behavioral teratology” of mercury for better understanding of effects of prenatal exposure to mercury and its compounds in addition to commentary on history and framework of behavioral teratology.