Elevated and low levels of maternal serum alpha-fetoprotein in the midtrimester of pregnancy have been linked with adverse events in later gestation, such as fetal and neonatal deaths, chromosomal abnormalities, and low birth weight infants. It is not known if this same association with poor pregnancy outcome is also true of amniotic fluid alpha-fetoprotein. In this study, alpha-fetoprotein was obtained from the fluid of 1060 women undergoing genetic amniocentesis for advanced maternal age. Poor pregnancy outcome was defined as (1) a fetal or neonatal death, (2) preterm delivery, or (3) low birth weight infants. Amniotic fluid alpha-fetoprotein was compared to each type of adverse outcome. No significant association with a poor pregnancy outcome in later gestation was noted. Although serum alpha-fetoprotein in the midtrimester of pregnancy may relate to certain poor outcomes in later gestation, midtrimester amniotic fluid alpha-fetoprotein offers no predictive value for the course of events in later gestation.