Little is known about the long-term effects of prenatal exposure to alcohol. There are even fewer reports on the longitudinal effects of exposure to either marijuana or tobacco during pregnancy. This study is on the 6-year follow-up of 668 children enrolled in the Maternal Health Practices and Child Development Project. Mothers were interviewed at the 4th and 7th months of pregnancy, and mothers and children were evaluated at delivery, 8, and 18 months, and 3 and 6 years postpartum. At 6 years of age, children who were exposed to alcohol prenatally were significantly smaller in weight, height, head circumference, and palpebral fissure width. These effects on sire were mediated by the effect of prenatal alcohol exposure on the offspring at 8 months. Prenatal alcohol exposure was also significantly associated with maternal reports of the child's appetite at 6 years. There were no effects of prenatal marijuana or tobacco exposure on growth when the children were age 6. There were also no significant relationships between prenatal exposure to alcohol, marijuana, or tobacco and the rate of morphologic anomalies, including the features of the fetal alcohol syndrome.