Several studies in rats have found that maternal administration of low or moderate doses of ethanol result in fetal perception of the chemosensory and toxic effects of ethanol. This prenatal experience with the drug enhances the palatability of ethanol's flavor and increases ethanol consumption during infancy and adolescence. The acquired preference for ethanol seems to be a conditioned response established prenatally, by the association of ethanol's sensory and reinforcing aspects, the latter mediated by the opioid system. These results are in accordance with data of studies in humans, and should be taken into account for clinical studies analyzing the relationship between prenatal ethanol exposure and later ethanol abuse problems.