Structural malformations and growth retardation are commonly observed in chromosomally abnormal newborns. This study assesses the sensitivity of ultrasound for detecting aberrant fetal growth patterns and chromosome-related major malformations. The study population consisted of 74 trisomic fetuses (trisomy 13, 9; trisomy 18, 22; trisomy 21, 43). Overall, 63% (38 of 60) of trisomic fetuses had at least one major malformation on postnatal examination. One or more major anomalies were identified by prenatal sonography in 68% (26 of 38) of these malformed fetuses and 43% (26 of 60) of the entire trisomic population. Midtrimester onset growth retardation was evident in 43% of fetuses with trisomy 13 and 59% of fetuses with trisomy 18. These findings suggest that a systematic fetal anatomic survey can be a powerful screening tool for the prenatal detection of chromosome abnormalities.