Three mothers of infants with holoprosencephaly consumed alcohol heavily in pregnancy. We postulate that early alcohol exposure is a possible cause of their malformation. The 3 mothers consumed alcohol only in the first trimester but the first mother continued to take chlordiazepoxide and imipramine throughout the pregnancy. Her infant had an alobar holoprosencephaly associated with a median cleft lip, ocular hypotelorism, and a flat nose. The other infants had semilobar holoprosencephaly and hydrocephalus. These latter 2 infants did not show the characteristic facies of the fetal alcohol syndrome. G-band chromosome studies were normal in all 3 infants. The association of holoprosencephaly with alcohol exposure during pregnancy in humans has been mentioned only briefly, although this malformation has been induced by alcohol in animals. These 3 infants may support the hypothesis that acute or subacute heavy alcohol exposure early in pregnancy could lead to holoprosencephaly without the necessity of a chronic alcohol exposure and without necessarily causing the typical facial findings of the fetal alcohol syndrome.