Detection of fetal developmental abnormalities by ultrasound examination of pregnant women has become a specialized field of medicine. Quality control of this field requires detailed examination of aborted fetuses. In 408 fetuses and infants with developmental anomalies, the prenatal ultrasound findings were compared with the post-mortem findings. This study focused on 140 central nervous system (CNS) anomalies. Criteria for inclusion were an ultrasound examination at the National Center for Fetal Medicine (NCFM) and an autopsy performed during the period 1985-94. Results of the ultrasound and autopsy examinations were systematized into six different categories. Hydrocephaly and anencephaly were the most frequent abnormalities, together accounting for 50% of the CNS anomalies. In 20 cases (14%), the CNS anomalies were associated with other important anomalies or chromosomal aberrations. In 125 of the cases (89%), there was complete concordance between the ultrasound and autopsy diagnoses. Of the 15 CNS cases with discrepancies, seven had nearly complete concordance; if we include these, the correlation was 94%. In conclusion, this study confirms that developmental anomalies in the central nervous system are frequent and that ultrasound diagnoses are in good concordance with the autopsy diagnoses.