Sixty-three patients with antenatally diagnosed fetal malformations over the period of 14 months were prospectively offered genetic amniocentesis, irrespective of gestational age. An additional 15 patients were excluded from the study because of a known lethal malformation (13 anencephaly, two amniotic bands). Twenty patients accepted amniocentesis, and seven chromosomal disorders were found. Obstetric management was altered in some of these patients as a result of the anomalies.