A non-human primate model for the fetal alcohol syndrome (FAS) has been developed in a pilot study on four pigtailed macaques (Macaca nemestrina) receiving ethanol once weekly from 40 days of gestation (2.5 g/kg for three moderate-dose monkeys and 4.1 g/kg for one high-dose monkey). Ethanol and acetaldehyde levels and indices of general health were monitored throughout pregnancy. One pregnancy ended in miscarriage. The three infants born at term were compared to control infants. The infant exposed to the higher ethanol dose showed phenotypic similarities to humans with FAS. Its brain was microcephalic and dysplastic; reflex, motor and cognitive development were retarded. One infant receiving the moderate dose had subtle brain abnormalities; it was hyperkinetic and showed developmental retardation on several behavioral measures. The other moderately dosed infant was normal. A larger study now in progress will comprise six groups of seven monkeys, each group being exposed to 0 (control), 0.3, 0.6, 1.2, 2.5 or 4.1 g/kg of ethanol once weekly throughout gestation. So far, 4.1 g/kg ethanol has been shown to be fetotoxic when given between 8 and 13 days of pregnancy.